1. They were walking along the shore _______ a huge wave appeared out of nowhere, sweeping them out to see.

A. as                B. while         C. when         D. though

2£®—Why didn’t you try your best to get on the bus?

—I tried to , but _______ I could, it started moving.

A£®before             B£®when               C£®until                D£®after

3. It’s already 10 o’clock. I wonder how it_______ that she was two hours late on such a short trip.

A. came over       B. came about        C. came out      D. came up