孔隙比e可以简单的判定砂土的密实状态，孔隙比愈小，表示土愈密实。
参考答案：对
丙硫氧嘧啶的主要适应证有中、轻度甲亢和单纯性甲状腺肿。( )
He studied very hard all the time because he didn’t want to __________in his studies.
A．fall behind
B．be left behind
C．left behind
D．Both A and B
