在程序句中，冒号前最多可以使用20个单词。
A.In procedural sentences, you can use a maximum of 20 words before the comma （逗号） B.In procedural sentences, you can use a maximum of 20 words before the colon. C.In procedural sentences, you 'can use at least 20 words before the full stop （句号）.正确答案B
