搜题请搜索小程序“爱下问搜题”
问题
单项选择题
成熟B细胞的表面标记是
A．CD3
B．CD4
C．CD8
D．CDl9
E．CD45
答案
参考答案：D
选择题
John had to have his car repaired in a garage because it ____ seriously.
A. damaged
B. was being damaged
C. had damaged
D. had been damaged
查看答案
单项选择题
在国际贸易中，影响产品的最终价格的是______
A．生产成本
B．流通费用
C．关税
D．利润
查看答案
