Simon prepared _____ a letter to ask Jim for some _____.   [ ]

A. to write, advice

B. to write, advices

C. writing, advice

D. writing, advices

两手握单杠，一腿挂杠的悬垂称为什么（）

A.倒挂膝

B.单挂膝

C.单纯悬垂

D.混合悬垂