John received an invitation to dinner, a

在数据库的三级模式结构中，内模式可以有 ______。

A．1个

B．2个

C．3个

D．任意多个

甲公司以人民币为记账本位币，发生外币交易时采用交易日的即期汇率折算。甲公司12月20日进口一批原材料并验收入库，货款尚未支付；原材料成本为80万美元，当日即期汇率为1美元=6.8元人民币。12月31日，银行存款美元户余额为1000万美元，按年末汇率调整前的人民币账面余额为7020万元，当日即期汇率为1美元=6.5元人民币。上述交易或事项对甲公司12月份营业利润的影响金额为（）万元人民币。

A.-220

B.-496

C.-520

D.-544

患者，女，30岁，已婚。产后小腹剧痛，拒按，恶露量少，色紫黯有块，块下痛减，舌淡黯，脉沉弦或沉紧。治疗应首选（）

A.生化汤

B.当归建中汤

C.肠宁汤

D.失笑散

E.血府逐瘀汤

能把外来的尘粒、细菌等和黏液一起送到咽部的结构是[ ]

A．气管软骨    

B．腺细胞    

C．气管纤毛    

D．喉

Microwave communication uses high-frequency (71) waves that travel in straightlines throughthe air. Because the waves cannot (72) with the curvature of the earth, they can be (73) only over short distance. Thus, microwave is a good (74) for sendingdata between buildings ina city or on a large college campus. For longer distances, the wavesmust be relayed by means of"dishes" or (75) . These can be installed on towers, highbuildings, and mountain tops.

A．optical

B．radio

C．electrical

D．magnetic