It's Charlie's birthday today, but he isn't feeling happy. No one wishes him a happy birthday. Mother says nothing about his birthday. She just tells Charlie to play outside. At lunchtime, his mother calls, "Come in for lunch, Charlie!" Charlie slowly walks into his house. But the living room looks different. Charlie sees a big "Happy Birthday"banner(横幅). Then, he sees a birthday cake, balloons, presents, and all of his friends. "Happy birthday!" everyone shouts. Charlie’s face lights up. He is happy and surprised(吃惊). No one forgets his birthday after all!

①江主席是学工程的，没想到他对古典文学如此熟悉，我真打心眼里佩服他！（改为反问句）

②她深有感触地说：“我小时候总是羞羞答答的。”（改为不用引号的句子）

③在原句上修改病句。

Ⅰ两辆新旧自行车骑起来就是不一样。

Ⅱ观看着优美的舞蹈，悦耳的音乐，大家高兴极了。

假定某大肠杆菌含¹⁴N的DNA分子的相对分子量为a，若将其长期培养在含¹⁵N的培养基中，得到含¹⁵N的DNA，相对分子量为b，现在将含¹⁵N的DNA分子大肠杆菌再培养在含¹⁴N的培养基中，那么，子二代DNA的相对分子量平均为（  ）

如图所示、为在某十字路口附近的一橡胶减速带，一警用巡逻车正以20m/s的速度行驶在该路段，在离减速带50m时巡逻车开始做匀减速运动，结果以5m/s的速度通过减速带，通过后立即以2.5m/s²的加速度加速到原来的速度．警用巡逻车可视为质点，减速带的宽度忽略不计．求由于减速带的存在巡逻车通过这段距离多用的时间．