Is there a general rule for Verb + Preposition/Particle idioms, such as "come across"?

Question

Composite verbs are giving me a lot of trouble. In German the syntax is simple; if the composite verb has the moving part, it goes to the end. But in English I've found many forms and I'm not sure which to use.For example, which of those would be correct and why?>* I've come across him yesterday.* I've come him across yesterday.* I've come him yesterday across.

Answer 1

Some phrasal verbs are separable and some are inseparable. I'm sorry to say that there is no rule for distinguishing between the two types. They must be learned one by one. "Come across" is inseparable; therefore, "I came across him yesterday" is correct. (Since you included a specific time in the past in your sentence (yesterday), it would not be correct to use the present perfect tense.) I know this wasn't the answer you were hoping for. Sorry.