—Who can help me carry the heavy box?
—I think David is _______ to do it. But the door is ______for him to go through.
A:too strong; too narrow
B:too strong; narrow enough
C:strong enough; too narrow
D:strong enough; narrow enough
下面句子的方框里,可以使用问号的一项是( )
下列各组词语中,没有错别字的一项是( )
已知关于x,y的二元一次方程(a﹣1)x+(a+2)y+5﹣2a=0,当a每取一个值时,就有一个方程,而这些方程有一个公共解,试求出这个公共解.