Polly’s mother was anxious about ______ she could get home safely in ______ foggy a day

How about the book you are reading?— Good indeed. It _______many problems we havecome across in our study.[ ]

What do you have ____ for Paul一I think he should study harder than before.

The students_ _to be very strict with themselves in their study and work.

The soldier raised his gun and calmly _____ it at the enemy commander, fired. [ ]