一般来讲,高氟区的界定是饮水中氟的含量超过()
A.0.5mg/L
B.1.0mg/L
C.1.5mg/L
D.2.0mg/L
E.2.5mg/L
参考答案:B
What vegetable ____________ the letter " a " ?[ ]
A. has
B. have
C. are
“Have you seen the film?” he asked me. →He asked me _______.
A.had I seen the film
B.have I seen the film
C.if I have seen the film
D.whether I had seen the film