人体血管中，管壁最厚的是____ ，管腔最大的____ ，血流速度最快的是____ ，血流速度最慢的是____ 。

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).