Is/Will

Rishonly wrote:

Anonymous wrote:  "i don't know when he'll..."...we can't use "will..". Hi, Your example is fine to me and it doesn't violate any grammar rules. The tricky part is identifying the function of "when" in sentences. If  "when" is used as a time adverbial conjunction in a sentence, then "when...will"  construction in the subordinate clause is wrong. Nonetheless, in your example, "when" is not a time adverbial conjunction rather it just begins an indirect question. So, it is OK to use "will"  after "when" in the indirect questions.  For example, the following sentences are indirect statements and "when" begins an indirect question. In these sentences, the usage of "when" after "will" is valid. I don't know when he will..... I am not sure when he will..

CalifJim wrote:

we can't use "will" after "when".. Not true.  We can't use will after when if when is an adverbial conjunction of time, that is, if it tells when something happens.  We can use will after when if when simply introduces an indirect question, typical after expressions like I don't know or I can't guess or I have no idea. In the case above, the when clause when he will come does not tell us when 'I don't know'.  'I don't know' at all times, or in general.  My lack of knowledge is not restricted to the moment in time described by the when clause.    It's an indirect question.  When will he come?  I don't know. CJ