A：5
B：6
C：7
D：8
This is a picture of Mr. Li's family. The man in the middle is Mr. Li. The woman is Mr. Li's wife. They have two sons. The child behind Mr.Li is Li Lei. He's thirteen. The other in front of Mrs. Li is Li Ming. He is eleven. Li Lei and Li Ming are in the same school, but not in the same grade. Li Lei is in Grade Two. Li Ming is in Grade One. They are good students.
关于家庭电路及安全用电的理解，正确的是（ ）
身高突增是青春期的一个显著的特点，其中女孩子的发育早于男孩。
11月23日，我国宣布：划设 防空识别区。防空识别区是基于国防需要划设的预警区域。（ ）
