下列哪项属于吸气性呼吸困难
A．支气管哮喘B．慢性支气管炎C．甲状腺肿大D．大片肺不张E．气胸
参考答案：C
根据所给单词及句子意思, 填入单词的正确形式.
1. Do you mind _________ (close) the windows?
2. They enjoyed _________ (fly) the kites.
3. We told him _________ (not break) the glass.
4. What do you think of _________ (swim) in the river?
5. Can you please _________ (not paint) on the wall?
6. Can you please put my opinions in the _________ (month) newspaper?
7. I think Hilltop High is the _________ (cool) of the movies.
8. How about _________ (go) to the mountains on vacation?
9. They see many _________ (color) clothes.
10. The students' answers _________ (surprise) their teachers.
在粒子ABn或ABnm±中，若元素的化合价的绝对值=原子A的最外层上的电子数，则粒子ABn或ABnm±的空间结构对称--呈非极性，换句话说，只要其中原子的最外层上的电子全部成键，那么该粒子就是非极性的．在①CH4 ②PCl5 ③BF3 ④NH4+ ⑤NO3- ⑥SO42-（ ）
A．只有①②③
B．只有④⑤⑥
C．除④外都是
D．全部都是
