At times, this can be risky, and the keepers have been injured and one has been killed.

At times, this can be risky, and the keepers have been injured and one has been killed.

A. good

B. useful

C. healthy

D. secure
Xem đáp án
D là đáp án đúng
Lời giải:
risky: mạo hiểm >< secure: an toàn