预防子宫脱垂不正确的是（）

A.产后避免过早参加体力工作

B.尽量行剖宫产术

C.推行计划生育

D.产后早期盆底肌肉锻炼

E.积极治疗咳嗽、便秘

One of the very important documents in the foreign trade business is BL. B/L is the abbreviation for ______.

A．Bill of Lading

B．Commercial Invoice

C．Buying Contract

D．Letter of Credit