图1表示大草履虫和双小核草履虫单独培养时的数量变化.图2表示两种草履虫混合培养时的数量变化.

请回答问题:

在“验证力的平行四边形定则”实验中，先将橡皮条的一端固定在水平木板上，另一端系上带有绳套的两根细绳．实验时，需要两次拉伸橡皮条，一次是通过两细绳用两个弹簧秤互成角度地拉橡皮条，另一次是用一个弹簧秤通过细绳拉橡皮条．同学们在操作过程中有如下议论，其中说法正确的是（   ）

给加下划线的字选择恰当的解释，把序号填在括号里。

在这次作战中，他身负重伤。（    ）

补全对话

从方框中选择最佳选项完成对话, 有两项多余

a. I'm cleaning the house.

b. Is your mother making dumplings with her?

c. What about your father?

d. Yes, we are.

e. She is buying some food in the shop.

f. What's your mother doing?

g. They are making cards for their family and teachers.

Daming: Hi, Tony! Are you getting ready for Spring Festival?

Tony:____ 

Daming: What are the girls doing?

Tony:____

Daming:Sounds great(听起来很好)! Where is your mother?

Tony:____

Daming: What are you doing?

Tony:____

Daming: How hard you are working! And is your sister helping you?

Tony: No, she isn't. She is shopping with my mother.

Daming:____

Tony: Look! He's painting the door there.