以下选项均为艾滋病的传播途径，而我国目前最主要的传播途径是（）
A.注射途径
B.性接触途径
C.母婴垂直传播途径
D.人工授精
E.器官移植
参考答案：A
I will________ some money from him but I will _______my bike to him in a few days. [ ]
A. borrow, return
B. lend, borrow
C. borrow, lend
D. lend, keep
如图所示的是用游标卡尺测量钢管外径时的示数，则这根钢管的外径是__________mm。
