一个两位数，十位上的数字为m，个位上的数字为n，则这个两位数是 [ ]
A.mn
B.10m+n
C.m+n
D.10mn
答案：B
偏瘫患者进行床-轮椅之间的转移时轮椅放在健侧，与床成夹角是（）。
A.＜30°
B.30°～45°
C.40°～45°
D.45°～50°
E.50°～60°
My cell-phone has disappeared. Who ____ have taken it away?[ ]
A. could
B. should
C. must
D. might
