题目

句型转换。【1】It is very important that we are in a good mood. (改为简单句）It is very important ______ ______ ______ ______ in a good mood.【2】Many things around us affect our feelings and moods. (就划线部分提问）______ affect ______ feelings and moods?【3】We should try to prepare for the meeting. (改为同义句）We should try to ______ ______ ______ the meeting.【4】Why not finish your homework first? (改为同义句）______ ______ ______ ______ your homework first?C3N4是一种新型材料，它的硬度比金刚石还高，可做切割工具。C3N4中C的化合价与CO2中C的化合价相同，则N的化合价是A．-2B．-3 C．-4 D．+3