根据句意和汉语提示，填写单词。

1. An old woman won five _____ (百万) yuan in the lottery ( * * 抽奖).

2. You look unhappy today. Please tell me your _____ (烦恼的事情).

3. His father was wearing a white shirt and a red ________(领带).

4. The book was the result of ten years of medical _____ (研究).

5. The famous singer gave much money to _____ (慈善事业) to help homeless children.

“探究加速度与力、质量的关系”的实验装置如图所示，用该装置研究小车加速度a与质量M的关系时，下列说法正确的是（   ）

A．先释放小车，再接通电源

B．打点计时器接电源直流输出端

C．牵引小车的细绳应与长木板保持平行

D．在增加小车质量的同时，增大木板的倾角