网址：http://m.1010jiajiao.com/timu3_id_2640388[举报]
Listen! Who ________ (sing) in the next room?
Listen, who______ in the classroom?
A．sings
B．sing
C．is singing
D．singing
Listen! Who ________ in the next room?
A．
sings
B．
is singing
C．
sing
D．
sang
Listen!Who ________ in the classroom?
singing