English usage

I have some questions about specifc words:
(1)"made compulsory"and "made as compulsory":
Learning English should be (made compulsory) at school.

can I insert an "as" after compulsory? Or is it necessary?

(2)prepositions, with and by:
I was found to have been infected (by/with) a strain of H5N1
which is correct? by or with?please explain

(3)prepositions,into and off
This could be set (off/into) the next influenza, killing millions of people.

"into" is probably incorrect, why?

(4)choices of words
The problem is that (each/the) time the virus mutates, a number of people will die

I choose "the", and it is incorrect. Why?

(5) choices of words

No(exceptions/wonder) whenever a man is found to have SARS, he will be isolated together with his family.

exceptions is probably incorrect, even if a phase "there are" is inserted in the front. Why?

(6)choice of word

They are frustrated by the (fact/trend) that the virus we are most worried about hasn't yet developed.

fact or trend? Why?

Thank You

[MrPedantic]

Hello Cheung

(1) No, it would not be idiomatic to insert "as".

(2) a) "I was found to have been infected by a strain of H5N1" ] This makes H5N1 sound like the agent of infection, instead of the infection itself. Cf. "I was slapped by a large Uruguayan", where the Uruguayan is the agent.

However, "infected by" is quite common among native speakers, in such contexts.

(2) b) "I was found to have been infected with a strain of H5N1" ] This seems like the normal version, to me.

(3) "This could be set off" sounds a little strange here; did you mean "this could set off another influenza epidemic"?

(4) Here, we have several occasions. We want to specify that something happens on every one of those occasions. Thus "...each time the virus mutates..."

(Also, "the time the virus mutates" wouldn't be idiomatic!)

(5) I find both "no exceptions" and "no wonder" a little strange. "Without exception" might work.

(6) "the trend that the virus...hasn't yet developed" makes "trend" the object of "develop". But it wouldn't make sense to say that a virus had developed a trend.

MrP