根据首字母写出正确的单词形式.

1. Edward d_______ himself to scientific research after graduating from university.

2. Most of the Americans v_____ for Obama to be president.

3. The design of the product must be r______ to people’s needs.

4. The fire started in the middle of the night, so most of the people were t_____ in the burning building.

5. The thief used a false i_____ to take money from the bank.

下列关于说法中正确的是（　　）

A．物体只有重心处受到重力的作用

B．图中足球与斜台作用时斜台给足球的弹力沿垂直于斜台斜向左上方的方向

C．一对相互作用力的合力为零

D．将大小为10N的力F分解为F₁和F₂，其中F₁与F的夹角为30°，则F₂的大小可为6N