. ---Why do you say that the doctor is in a _______? ---Because he doesn’t know whether to tell the patient the truth or not.

This new-type machine ____.

I listened to Dr.Wilson’s lecture about the protection of wild animals,but I was unable to grasp its key _________.

Scientists have to work hard to keep _____ with modern discoveries and developments.

My first _______ of him was that he was a kind and thoughtful young man.