下列（）不是液体散装化学品的主要特性。
A．易燃性
B．毒害性和腐蚀性
C．化学反应性
D．自燃自热性
参考答案：A
He often_______ tennis with his friends. Now they_______ tennis at school.
A．play; play
B．plays; playing
C．plays; are playing
D．playing; are playing
如果一对孔、轴装配后有间隙，则这一配合一定是间隙配合。
