cad＝to fall（落下） 变化型 cid，cas
adj [usu attrib 通常作定语]
1 happening, coming, done, etc from time to time; not regular 偶然的; 偶尔的; 非定时的
*He pays me occasional visits. 他偶尔来看看我.
* There will be occasional showers during the day. 白天将偶有阵雨.
* I drink an occasional cup of coffee; but usually I take tea. 我偶尔喝杯咖啡, 但平常都喝茶.
* He reads the occasional book, but mostly just magazines. 他偶尔也看书, 但大多只看杂志.
2 (fml 文) used, meant, written, etc for a special event 应时的; 应景的; 为某场合的
*occasional verses, eg written to celebrate an anniversary 应景诗
* occasional music for a royal wedding 皇家婚礼上的应制音乐.
adj [only before noun]
happening sometimes but not often or regularly
He made occasional visits to London.
They had an occasional coffee together after shopping.
He only has occasional use of a car.
We should have enough money left for the occasional trip.
1. With occasional mistakes, of course." 当然，偶尔也会犯一些错误。"
2. The key is to be satisfied with gradual improvement, expecting and accepting the occasional slips that come with any change. 关键是你要对逐渐的进步感到满足，要预见到并接受可能伴随这种改变而来的偶尔失误。
3. One bought three of her original drawings, and she did occasional work for the other, sketching a lot of whales, dragons, castles and mythical animals. 其中一家买下了她的三张原创画作，而在另一家，她偶尔兼兼职，画了大量的鲸鱼、龙、城堡和传奇动物。
4. I get an occasional letter from him , that´s all. 我收到他偶而写来的一封信，如此而已。
5. Which may keep company with the vessel for an hour without visible or more than occasional movement of wing. 它们随船飞行一小时也难得见其扇动一下翅膀。