举例说明式量相等的物质不一定是同一种物质？
参考答案：
例如H2SO4和Cu（OH）2的相对分子质量都是98，N2和CO的相对分子质量都是28.
He was told that it would be at least three more months _____ he could recover and return to work.
A．when
B．before
C．since
D．that
领导干部提高法治思维和依法办事能力，关键要做到哪些？
