Our teachers are really . They often work in their office far into the night.A. open-minde

问题补充：

Our teachers are really . They often work in their office far into the night.

A. open-minded

B. hard-working

C. self-confident

D. warm-hearted

答案：

A. open-minded

(答案→)B. hard-working

C. self-confident

D. warm-hearted

解析：考查词义辨析。open-minded心胸开阔的，hard-working 勤劳的，self-confident 自信的，warm-hearted 热心肠的，句意：我们真得很勤劳。他经常在办公室工作到深夜。所以选B。