差速器的功用是什么？
参考答案：差速器的功用是当汽车转弯行驶或在不平路面上行驶时，使左右驱动车轮以不同的转速滚动，即保证两侧驱动车轮作纯滚动运动。
—I don't know if Mr Li________to the party this evening.
—I think he will come if he _______ free. [ ]
A. will come; is
B. will come ; will be
C. comes ; is
D. comes; will be
苏式彩绘
