—They ______.
A:play football
B:playing football
C:are playing football.
2015年“地球日”活动中,中国区主题是“能见蔚蓝”.“能”意味着可再生能源能够带来改变,“蔚蓝”代表每个人对告别雾霾、寻回蓝天的期待.下列能源资源中,属于可再生能源的是( )
—The cake smells ___________ bad.
—It goes ___________ easily if you don't keep it in the fridge.
青藏高原终年雪山连绵,原因是( )