在换流阀的设计和制造中应采用（）材料，并消除火灾在换流阀内蔓延的可能性。
参考答案：阻燃
灵敏度是输出量的增量与（）之比。
—Jack can't concentrate on his lessons recently.
—Yes, that might ____ why he did so badly in the last test.
A．answer for
B．apply for
C．call for
D．account for
