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).

为探究物质的燃烧条件，某同学进行了如图所示的实验，下列有关说法正确的是____ ．

A．现象①③说明白磷的着火点比红磷的着火点低

B．现象①②说明物质的燃烧需要温度达到着火点

C．现象②说明物质必须是可燃物

D．现象①③说明____ ．