过量饮用咖啡对人体的不良影响有()
A、导致血压升高
B、预防胆结石
C、抑制新陈代谢
D、促进血液循环
参考答案:A
某校操场原有面积2800m2,因扩建,把宽从40m增加到50m,长不变.扩建后的操场面积比原来增加多少m2?
In American, a friend inviting you to a restaurant doesn't mean that he or she will pay for the meal ______ you are told ahead.
A.until
B.unless
C.although
D.if