Ⅰ.单句语法填空
1．As is known to all, the sun ________ (rise) in the east and ________ (set) in the west day after day.
rises; sets [句意：众所周知，太阳东升西落，日复一日。表示客观事实、客观规律要用一般现在时。]
2．Tom ________ (cry) again and again and we can't bear him anymore.
is crying [句意：Tom一直在哭泣，我们再也忍受不了他了。进行时与某些副词连用可表示说话人的一种强烈的感情，如厌恶、欣赏、钦佩等。]
3．It has been three years since we ________ (come) here.
came [句意：自从我们来到这儿已经三年了。since＋含有一般过去时的句子/表过去的时间点，主句或句子常用现在完成时。]
4．By the time he was nine, Tom ________ (master) a foreign language.
had mastered [句意：到九岁时，汤姆已经精通了一门外语。by the time表示“到……的时候”，引导时间状语从句时，如果从句用一般过去时，主句要用过去完成时。]
