Reference, courage and measurement

Pitfall: 不能 and 不敢 describe different reasons for not acting.

各小组 each group; 各位老师 teachers addressed respectfully; 各种问题 various kinds of problems; 任何人 anyone; 此事 this matter in written language. These expressions do not share exactly the same noun-combination rules.

Pitfall: 此 is more formal than 这 and does not fit every conversational context.

一打鸡蛋 a dozen eggs; 一袋米 a bag of rice; 一棵树 a tree; 一台电脑 a computer; 一幅画 a picture. Classifiers can encode different ways of packaging the same broad category of thing.

Pitfall: 棵 counts trees; 颗 is used for small rounded things at a later source level.

一脸汗 a face covered in sweat; 一手泥 a hand covered in mud; 一盒糖 a box of sweets; 一屋子人 a roomful of people; 一桌子菜 a tableful of dishes. Borrowed measures often express a whole container or surface's contents.

Pitfall: This does not literally count one face as an independent object.

一场比赛 a match; 吃一顿饭 have a meal; 跑一趟 make a trip. A bout of scolding may be 骂一顿, illustrating that measure words extend by event type rather than by simple dictionary noun labels.

Pitfall: 一趟 emphasizes a trip, while 一次 simply counts an occurrence.