We are going to discuss the way of reading works ______ it is used for real life purposes, and this should give you a better understanding of it.

A．that
B．which
C．where



D．when

正常胃充盈后胃壁有几层，回声特点是什么（）

A.3层；二强、一低回声，相间平行排列

B.4层；二强、二低回声，相间平行排列

C.5层；三强、二低回声，相间平行排列

D.6层；三强、三低回声，相间平行排列