16、 weather permits, we’ll have an outing.

A．For                B．Though           C．While             D．If

17、You won’t succeed      harder.

A．unless you will work     B．unless you work   C．unless you don’t work D．if you won’t work

18、I wonder if he         us, and I think if he      us we’ll be able to complete the task ahead of time.

A．helps, helps           B．will help, helps    C．helps, will help     D．will help, will help

19、I don’t like to be interrupted if I          .

A．speak                 B．will speak       C．am speaking         D．spoke

20、If you      this experiment you will understand the theory better.

A．will be doing          B．have done       C．will have done              D． would do

16、D  17、B  18、B      19、C  20、B