72÷8＝____，再乘4得____．

在△ABC中，$\overrightarrow{AB}=\left(2,3\right)$，$\overrightarrow{AC}=\left(k,1\right)$，$A=\frac{\mathrm{\pi }}{2}$，则k的值为(     )

根据句意及汉语提示，写出各单词的正确形式。
⑴We'll have to____ （训练）before the next match.
⑵Our teachers often ____  (鼓励)students to ask questions in class.
⑶The girl ____  (尖叫) when she saw the snake.
⑷The old man is very sick. He takes a lot of ____  (药) every day.
⑸____  (令人伤心地), many people still don’t want to take any actions to protect the animals.
⑹It is really ____ (幸运的) for me to pass the driving exam .
⑺ Millie didn't clean the room last week, she visited her friends____  (代替).

比较大小：-$\frac{3}{4}$____-$\frac{2}{3}$．