在长为3a+2,宽为2b-1的长方形铁片上,挖去长为2a+4,宽为b的小长方形铁片,求剩余部分面积。
解:(3a+2)(2b-1)-(2a+4)b=4ab-3a-2
A smile can help us _____________ difficult situations and find new friends in a world of strangers.
A.get across
B.get through
C.get out
D.get off
患者,男,30岁。昨日起胃脘胀痛,饮食不下,今天见呕吐频频。治疗应首选()
A.内庭
B.丰隆
C.太冲
D.内关
E.合谷