完成句子（共10分，每小题2分）
小题1:别担心，我一到上海就给你写信。
Don't worry. I'll write to you I get to Shanghai.
小题2:加强锻炼有益于你的健康。
It your health to take exercise.
小题3:我经常帮助杰克学英语。
I often Jack his English.
小题4:昨晚直到父亲回来我才睡觉。
I my father came back last night.
小题5:学生们花了一个小时才算出这道数学题。
It the maths problem.
小题1:Don't worry. I'll write to you as soon as I get to Shanghai.
小题2:It is good for your health to take exercise.
小题3:I often help Jack with his English.
小题4:I didn't go to bed until my father came back last night.
小题5:It took the students an hour to work out/solve the maths problem.
题目分析：
小题1:考查短语as soon as，一……就……。
小题2:考查短语固定搭配be good for，对……有好处。注意本句主语it是单数第三人称，故系动词用单数。
小题3:考查固定搭配help sb with sth帮助某人做某事。注意本句主语I是第一人称单数，一般现在时态中谓语动词用原形。
小题4:考查固定搭配not……until……，直到……才……。
小题5:考查take的用法。take 用于 it takes sb ... to do sth句型，仅指花费时间（three hours等），必须用it作形式主语，指代下文不定式内容。注意本句描述的是过去发生的动作，故用一般过去时态。