All the firemen in the city were ______to fight against the big fire.

A．called in

B．called off

C．called up

D．called on

Even if it ______ this afternoon, I will go there.

A．has rained

B．will rain

C．rains

D．will have rained

Science is still ______ of the causes of many kinds of cancer.

A．ignorant

B．unconscious

C．conscious

D．informed

I don't know his address, ______.

A．otherwise I will write to him

B．otherwise I would write to him

C．otherwise I had written to him

D．otherwise I would have written to him

Clearly the medicine ______.

A．may be dangerous for small children

B．can't be taken by children under twelve years old

C．may be taken by children but not by adults

D．may be taken by adults but not by children