He ran the 100 meters in 9.91 seconds, and I have not seen _________ this year.

It is important to keep ______ in an emergency (紧急情况).

With the help of the foreign experts, they produced ___ washing machines in 2003 as the year before.   

. People have always been_______about exactly how life on earth began.

I think you should go back to your          plan, which is much more practical than the present one.