We hope to finish our experiment________.

.．As is often pointed out, knowledge is a two-edged weapon which can be used_____________for good or evil.

Five firemen ________ escaped death when a staircase collapsed beneath their feet. 

Jack has a good habit of keeping a diary every day;      he is very good at writing.

—Do you think an advertisement is a help when you look for a job?—Well，it depends.________，it gives me a chance to try.