通过锦囊五:在下列短语或表达中须用不定冠词a(n)
1.have a swim/walk/talk/look; have a good time;keep a diary;in a hurry;have/lead/live a...life;once in a while;at a loss;once upon a time;tell a lie;all of a sudden;do sb. a favor;a mouthful of;at a distance等;
2.what/such/quite/rather a(n)+形容词+ 单数可数名词;
3.too/as/how/however+形容词+a(n)+单数可数名词;
4.many a(n)+单数可数名词;
5.not a(n)+单数可数名词;
6.half a(n)+单数可数名词。