David,turn off the TV ___ no one is watching it.But it ____ off already!The music is from the radio.A so that,has been turned B when ,has turned C if ,has been turned D because ,has turned可是为啥 if后面接的是is watching 而不是watches为什么是 has been turned 而不是 has turned
问题描述：
David,turn off the TV ___ no one is watching it.
But it ____ off already!The music is from the radio.
A so that,has been turned B when ,has turned
C if ,has been turned D because ,has turned
可是为啥 if后面接的是is watching 而不是watches
为什么是 has been turned 而不是 has turned
答