Hi,
I'm not sure everybody here understands what type of exercise you're referring to. I assume you are talking about the new format of the CAE, which will be introduced starting from December 2008, so I'm posting an excerpt from the
CAE handbook for teachers about part 5 (key word transformation) of paper 3 (English in Use).
Each question contains three parts: a lead-in sentence, a key word, and a second sentence of which only the beginning and end are given. Candidates have to fill the gap in the second sentence so that the completed sentence is similar in meaning to the lead-in sentence. The gap must be filled with between three and six words, one of which must be the key word. The key word must not be changed in any way.
In this part of the paper the focus is both lexical and grammatical and a range of structures is tested. The ability to express a message in different ways shows flexibility and resource in the use of language.
Here are some examples from the
CAE handbook for candidates:
1 There were a lot of things that we had to think about before we could accept their offer.
OBLIGED
There were several things that we ………………..……………….. consideration before we could accept their offer.
2 Do you think you could help me to fill in this application form?
WONDERING
I ………………..……………….. me a hand filling in this application form.
3 I know that it was wrong of me to shout in front of the customers.
RAISED
I know that I should ………………..……………….. in front of the customers.
4 If you need any help, you can always call me.
HESITATE
If you need any help, ………………..……………….. me.
As for your questions:
a) As a general rule, the tense in your sentence should mach that of the given sentence. For instance, in example no. 1 the original sentence has "...
we had to think about ...", so I'd write "...
we were obliged..." (both past simple). However, generalisations are dangerous, so if you're having problems with specific examples, I'd suggest you post them!
b) Yes, I have taken the CAE, but up to last June this exercise was not part of the CAE. However, I also took the FCE, which contained the key word transformation exercise.
c) My piece of advice: don't pay attention
only to the meaning of the sentence! Be also careful about the number of words you use (which must be between 3 and 6), especially when using contractions.
"Don't", "haven't", "I'm" and the like equal two words each (sorry, not sure about the grammar of this sentence!

), while "
can't" only accounts for one word (because it stands for "
cannot" => 1 word only).
Did I answer your questions? (Sorry, I'm not clear about the "
conditionals" part in your sentence "
Do you have some advise to find the solution with conditionals at this part.")