1. 开始行动：fall under 被归入 | fall upon 开始行动 | fall 秋天

2. 开始行动, 进攻：fall under 受到(影响等), 被归入. | fall upon 开始行动, 进攻. | fall upon the ear 被某人听到, 传到某人的耳朵.

3. 开始行动; 进攻开始行动; 进攻：fall under 受到; 被归入 | fall upon 开始行动; 进攻开始行动; 进攻 | fallacious 谬误的; 虚妄的; 靠不住的 (形)

verb

1. find unexpectedly

e.g. the archeologists chanced upon an old tomb
she struck a goldmine
The hikers finally struck the main path to the lake

Synonym: strikecome uponlight uponchance uponcome acrosschance onhappen uponattaindiscover