This means that if yacc would have to read two tokens before it knew which action to take, it would be unable to parse this grammar.
这就意味着，如果 yacc 在知道采取哪个动作之前，必须读取两个标记，那么它将无法解析该语法。
2
Grammar Expressing an action that is carried from the subject to the object; requiring a direct object to complete meaning.
一个表示从主体施向客体的动作，为了使意思完整需要一个直接宾语的。
3
Introduces and analyses some typical but often neglected expressions that show the aspect and state of an action from the Angle of communicative grammar of English.