下列物质中既有离子键又有共价键的是 A．MgCl2 B．SiO2 C．H2O2

方程2x+3y=27的正整数解是（    ）。

用所给单词的正确形式填空。

1. Jenny ___________ (run) with a kite on the playground now.        

2. I brush my ___________(tooth) in the morning and in the evening.  

3. The weather is cold and ___________ (cloud).                      

4. His aunt ___________ (make) dumplings now.                        

5. His brother___________ (drive) to work every day.                 

6. It's 9:00 now. The children are ___________ (have) an English class.

7. He lives near school. He ___________ (walk) to school.             

8. February  is the ___________(two) month in a year.                

9. How many ___________ (season) are there in a year?                

10. He often ___________ (watch) TV on Fridays.                        

气缸经过镗削加工后，其壁厚减少的尺寸，不得大于原来尺寸的（）。

A．1/3

B．1/6

C．1/9

D．1/12

女，45岁，右上腹绞痛，查体:皮肤、巩膜未见黄染，辅助检查:腹部超声示胆总管结石，血清总胆红素26μmol/L。该患者行血胆红素测定时，可出现哪种改变

A．血清总胆红素和非结合胆红素升高
B．血清总胆红素和结合胆红素升高
C．血清总胆红素和结合胆红素及非结合胆红素均升高
D．结合胆红素/总胆红素比值<20%
E．结合胆红素/总胆红素比值>35%

某日富滇银行外汇牌价表显示的美元牌价如下：现汇买入价：680.91，现钞买入价：675.55，卖出价：683.65，基准价：682.55。若客户将手中的100美元现钞兑换成人民币，则富滇银行应该向客户支付（）

A.￥680.91

B.￥675.55

C.￥683.65

D.￥682.55