题目

There are many rules in our school. For example, every student _______ the school uniform.A.have to wear B.has to wear C.have to wearing 答案：【答案】B【解析】句意：我们学校有很多规矩，例如，每个学生不得不穿校服。考查主谓一致。have to wear动词原形；不得不穿；has to wear第三人称单数；have to wearing错误。have to加动词原形，every student为主语，单数，用第三人称单数，故选B。下列事实与氢键有关的是（ ）A．HF、HCl、HBr、HI的热稳定性依次减弱B．水加热到很高的温度都难以分解C．CH4、SiH4、GeH4、SnH4熔点随相对分子质量增大而升高D．水结成冰体积膨胀