Hello teachers

This time I'd like ask you about form of the verb infinitives used as a complement. Let me show two sample sentences:
(1) My first task at work is to switch on the machine.
(2) The first thing I have to do at work is (to) switch on the machine.
I have learned we cannot leave out 'to' from 'to switch' in (1) but we can in (2).
Why can we leave out 'to' from an infinitive in the complement position when the subjective phrase contains 'do' or 'did'.?

paco

Hi, Paco,

This grammatical phenomenon comes under the heading of "pseudo-cleft" sentences, although your example (the second sentence you cite) is a modified form of it. Prototypical examples are:

What John lost was his wallet.
What caused the problem was a leaky faucet.
What the committee objects to is the third paragraph.
What I like most about her is her sense of humor.
What I'll use to pound these nails is a hammer.

In other words, the prototypical pseudo-cleft sentence consists of a "what" (nominal) clause and another nominal clause connected by "identifying be". (These are sometimes called 'equatives'.)

Expressed a little differently:

IDENTIFIED = IDENTIFIER

Here are some equatives which are not pseudo-clefts.

"An elephant is a mammal"
"Clinton and Reagan were presidents of the U.S."
"The girl sitting in the middle is my sister."

Leaving pseudo-clefts and equatives aside for a moment, note that "do" is a pro-verb. It can substitute for verbs (and their complements) , thus:

-- I work in a factory.
-- Really? I do, too.

-- I saw that movie.
-- I did, too.

-- I was perfraculating until midnight last night.
-- You were doing what until midnight?

Putting all these pieces together:
When pro-verb do is used in the IDENTIFIED position ("what" clause) of a pseudo-cleft sentence, the IDENTIFIER contains the verb for which do serves as the pro-verb. The form of that verb is determined by the form of the pro-verb do seen in the IDENTIFIED position ("what" clause): If "doing" is the form used, the verb in the IDENTIFIER position is also in the "-ing" form; otherwise it is the infinitive form, with or without "to". All this verbiage is much more easily seen in a few examples!

What he is doing is looking for a new car.
What they need to do is (to) talk to the boss about it.
What I did was (to) try a second time.

Your example is a slightly modified pseudo-cleft with pro-verb "do":
What I have to do first at work is (to) switch on the machine.
The first thing I have to do at work is (to) switch on the machine.

I hope that answers your question. (The short answer would have been: because "do" is a pro-form, but I'm not sure that would have been enough to get my points across!)

CJ

P.S. Your first example is not a pseudo-cleft sentence, so there we don't have the luxury of dropping the "to"!

CalifJim wrote:

Hi, Paco, This grammatical phenomenon comes under the heading of "pseudo-cleft" sentences, although your example (the second sentence you cite) is a modified form of it. Prototypical examples are: What John lost was his wallet. What caused the problem was a leaky faucet. What the committee objects to is the third paragraph. What I like most about her is her sense of humor. What I'll use to pound these nails is a hammer. In other words, the prototypical pseudo-cleft sentence consists of a "what" (nominal) clause and another nominal clause connected by "identifying be". (These are sometimes called 'equatives'.) Expressed a little differently: IDENTIFIED = IDENTIFIER Here are some equatives which are not pseudo-clefts. "An elephant is a mammal" "Clinton and Reagan were presidents of the U.S." "The girl sitting in the middle is my sister." Leaving pseudo-clefts and equatives aside for a moment, note that "do" is a pro-verb. It can substitute for verbs (and their complements) , thus: -- I work in a factory. -- Really? I do, too. -- I saw that movie. -- I did, too. -- I was perfraculating until midnight last night. -- You were doing what until midnight? Putting all these pieces together: When pro-verb do is used in the IDENTIFIED position ("what" clause) of a pseudo-cleft sentence, the IDENTIFIER contains the verb for which do serves as the pro-verb. The form of that verb is determined by the form of the pro-verb do seen in the IDENTIFIED position ("what" clause): If "doing" is the form used, the verb in the IDENTIFIER position is also in the "-ing" form; otherwise it is the infinitive form, with or without "to". All this verbiage is much more easily seen in a few examples! What he is doing is looking for a new car. What they need to do is (to) talk to the boss about it. What I did was (to) try a second time. Your example is a slightly modified pseudo-cleft with pro-verb "do": What I have to do first at work is (to) switch on the machine. The first thing I have to do at work is (to) switch on the machine. I hope that answers your question. (The short answer would have been: because "do" is a pro-form, but I'm not sure that would have been enough to get my points across!) CJ P.S. Your first example is not a pseudo-cleft sentence, so there we don't have the luxury of dropping the "to"!

Hi Calif, we both thanks for your excellent instruction. However, I wonder if pseudo cleft structure can go with which or not? Ex: Which I chose to do in the end was hit the hay