-- Anna, could you lend me this book, please?
-- I'm sorry. I it for only two days, and I haven't finished it yet.
A:have bought
B:have had
C:bought
D:had
组词写句
气____ ____
高____ ____
— A friend of mine.
①这列波的周期T= 2t3
②这亿波的周期T= t2
③这列波的传播速度v= 12st
④这列波的传播速度v= 16st
上述说法正确的是( )