请教两道语法,谢谢哦!

fhhrewr

1 ____C_____ are not leached out of soil, reclamation procedures are needed to restore the land’s productivity.
A. For concentrations of salt
B. Salt concentrations that
C. If salt concentrations
D. With concentrations of salt
为什么不选A?
2. In (the wild), tea plants become (trees) of (approximately) thirty feet in (high).
答案是 high,应改成height.
我认为approximately也错了,是不是应改成approximate??

himba

1. when "FOR" is a conjunction, 不放句首, 而放后半句. 2. 副词可以修饰数词