为自己加油

The installation should be commenced as soon as all the remaining problems have been cleared up.

A.待剩下的问题都解决之后就立即开始安装了。
B.待剩下的问题都解决之后就应立即开始安装。
C.所有遗留问题解决后，应立即开始安装。
D.所有遗留问题解决后，立即开始安装了。