问题补充:
to the left at the crossroads, and you will see the railway station on your right.
A. Turning
B. If you turn
C. Turn
D. Having turned
答案:
A. Turning
B. If you turn
(答案→)C. Turn
D. Having turned
解析:句意,在十字路口向左拐,你会看到火车站在你的右边。and 连接了两个并列句,and之前是一个祈使句,所以用动词原形,故选C。