题目内容：

阅读短文，根据短文内容，从短文后的五个选项中选出能填入空白处的最佳选项。每个选项只能用一次。

Careful and careless are as different as fire and water. But it is strange that quite a few scientists have both these qualities (品质). They are both careful and careless.

1..

Once Newton invited a friend to dinner at home. When they were ready to eat, Newton left to get a bottle of wine (酒). 2., Newton still didn’t come back. At last his friend found Newton in his lab. When Newton was going to get the bottle of wine, he suddenly had a new idea for his experiment. So he quite forgot his friend and the dinner. Another time, Newton was leading a horse up a mountain, and he held the rein (缰绳) in his hand. While he was walking along, he kept thinking about problems. 3. , he found that the horse was gone.

Einstein was another example. 4. . While waiting, he became lost in thought. It started to rain. The rain kept on for some time. When he took out a piece of paper to write something down, the paper was wet and then he knew that it was raining. 5. , he again forgot he was standing in the rain.