BS
参考答案:盐基饱和度是指交换性盐基离子占阳离子交换量的百分率。
— Do you often go swimming_____ Sunday mornings?
— Yes. Why not _____with me this Sunday?
A.on, go
B.in; to go
C.on; going
D.in going
John, work hard ________ you will make much progress.
A.or
B.nor
C.but
D.and