下列()方法为直流电法勘探方法。()
A. 电测深法
B. 电剖面法
C. 中间梯度法
D. 电磁法
He doubted ______ it was true.
A.if
B.that
C.as though
D.as if
What he needs is nothing _____ a few day's rest.
A. than
B. but
C. except
D. besides
The originally clean river is now seriously polluted and unfit _______.
A.to swim
B.for swimming
C.to swim in
D.for swimming in