Last Sunday, we went swimming in the pool. We enjoyed ____ (we).
You'd better put your heart into study. You see, the ________ you are, the ______ progress (进步) you'll make.
下列各式中,正确的是 ( )
某区域的电场线分布如图所示,a、b是电场中的两点,下列说法中错误的是( )