(x+y)2-( )=(x-y)2.
4xy
根据句意,汉语提示及首字母完成句子。
1. His favorite subject is social s_____.
2. My uncle knows about _____ ( 不同的) countries of the world.
3. She loves to _____ ( 旅行).
4. Li Lei is i_____ in Chinese.
5. The funny elephant is so i_____.
冬天某人入浴后突然晕倒,其原因是
A.全身血管收缩
B.血管容量增加
C.脑部缺血
D.血量减少