问题
Do you know a spaceship flies at about nineteen kilometers ________ second
A:the
B:a
C:/
D:an;
B:a
C:/
D:an;
正确答案是：
同类题型
Recently there have been many occasions____ you have attended events on your own
In front of the little garden stands the hospital, ______ is named after a famous scientist.
Sometimes I find it necessary to ______ at night because of too much homework.
mised that he ______ us in the party, but he hasn’t turned up until now.