_______ difficult the task may be, we must finish it on time, because we can’t meet such a precious opportunity _______ we have expected.

The Youth League Committee is looking for volunteers for the promotion of rubbish-sorting. Would you like to join in—________. Everyone should do his bit.

I will send you an e-mail as soonas I ______ in Canada.

With nothing ________ to burn, the fire became weak and finally died out before the firefighters came.

English is usefulsubject.