A:做成空心的
B:削掉一半
C:绑在木块上
①A的原子M层上有6个电子;
②B2+与D﹣具有相同的电子层结构,且可以相互组合形成常见干燥剂;
③元素C的单质常温为双原子气体分子,其氢化物水溶液呈碱性;
④元素D的最高正化合价为+7价.请回答下列问题:
①瓶A中上方气体的压强随液面的下降而增大;
②瓶A中液面下降,但A中上方气体的压强不变;
③滴壶B中的气体压强随A中液面的下降而减小;
④在瓶中药液输完以前,滴壶B中的气体压强保持不变.
用括号中所给单词的适当形式完成下列句子。 Davy enjoys____ (play) tennis and baseball.It will be____ (wind) in Sanya tomorrow.Nobody teaches her English. She learns it by____ (she).Jackie Chan is a famous____ (act). I____ (visit) my aunt on the farm last weekend.In China, September 10th is____ (teacher) Day.— Where is Amy?— She____ (go) to Guilin. She’ll be back next week.We can see many____ (potato) in the supermarket. Sometimes it rains____ (heavy) in Wuzhou in summer. My grandparents live on the____ (twelve) floor of a tall building.