Scientists say it may be five or six years _______ it is possible to test this medicine on human patients

Mr Johnson, we have found your watch.–My watch! Thank you. Where _____ it

Excuse me, could you tell me _______

In order to continue to live well when we leave school, we must _______ learn some useful skills as well as study in the school.

Believe it or not，I’m sure that is ________ people call the six sense.