6.Sound waves travel in the air in much the same way __________ water waves spread on the water.

6.Sound waves travel in the air in much the same way __________ water waves spread on the water.
A.as
B.that
C.where
D.in which
8.It wasn’t such a good present __________ he had promised me.
A.that
B.as
C.which
D.what
讲讲为什么,主要是什么时候用AS什么时候用that,3Q!