30－20＝____ 80－30＝____ 90－40＝____

10＋50＝____ 30＋60＝____ 70－70＝____

用括号内所给动词的适当形式填空。
The garden is the best place ____ (grow) flowers.
This pair of jeans ____  (match) his white shirt.
Listen! How wonderful the music____ (sound) ！
 Mary, ____  (not be) afraid of the dog. It never bites.
 Keep quiet, the students ____ (prepare) for the coming exam.
____  (ride) a bike to school is good for your health.
Sandy spends a lot of time____  (chat) with her e-friend on the Internet.
How long does it take you____ (walk) to school every day?
I don’t have any ideas, I don’t know where ____ (go).
Would you like____ (drink) a cup of tea?

小李的设计：将铁钉与盛有硫酸铜溶液的小试管装于烧杯中，加适当砝码使天平平衡，如图A。待烧杯内的物质完全反应后，观察天平否再次平衡。

小刚的设计：将盛有碳酸钠粉末的小试管放于盛有足量稀盐酸的烧杯中，加适当砝码使天平平衡，如图B。待两物质反应完全后，观察天是否再次平衡。

试回答下列问题：