重点讲解：
1. force sb. to do sth. 强迫；强制；
She forced herself to be polite to them.
她对他们强装客气#L]CgMOCLG#86SII。
2. start off 使开始；
The discussion started off mildly enough.
讨论颇为温和地开展起来j6e(ObL3#%^。
3. alternate with （使）交替；（使）轮流；
Alternate cubes of meat with slices of red pepper.
交替放置肉丁和红辣椒片Tv*kmqA(-+。
4. interfere with 妨碍；冲突；抵触；
She never allows her personal feelings to interfere with her work.
她从不让她的个人感情妨碍工作BWHHv77KpbYeZ[。