1.The car _will be going__at the present speed until it reaches the foot of the mountain at about ten o’clock tonight.
until 有直到...时间之前之意.at the present speed 是以目前行驶的速度.Will be doing 是将来进行时的形式.从目前直到山脚下这段时间的动作,要用将来进行时.所以要选择 Will be going 是将要继续行驶之意.其它三种形式都不对.
这句话的意思是,这辆汽车在今晚大约10点钟到达山脚下之前,将一直用当前的速度行驶.
2.He said it was important that every member send his subscription by the end of the month.
这一句是间接引语,主句的动词said是一般过去时,按说宾语从句也应当使用过去时态.但是从句里有一个短语 it is important that one should do something.这里的should 可以省略,就只剩下动词原形了.所以只能选 send.