My swimming experience is extreme interesting. There was a time when I swim like a rock. This went on till one day when I was fishing with a friend of mine at nearby pond. I slipped into one. Had my friend not come to my rescue, I would have been drowned. Ever since then, I had come to know the importance of learning to swim. I didn’t attend at any training class but learned it all by myself. Strange to say, I have difficult swimming at all now. Though the way I swim look awkward (笨拙的), at least it can keep me from floating. Thinking of this, I feel quiet satisfied.

前起落架开锁作动筒连接在哪个连杆上？（）

A.上部阻力支柱

B.下部阻力支柱

C.外筒

D.锁撑杆