Good English to help explain a few words

A has no grammatical errors, but the second sentence is better in the past perfect tense. So to speak:

when i arrived at the bus station， bus had left.

i no sooner arrived at the bus station than bus was gone.

b has grammatical errors, when the sentence after the sentence is missing the verb, when leads the sentence here, the complete subject-verb-object is needed, just add a were:

what did you say when you were from a to b?

Both of these sentences are sick sentences.

In the first sentence, replace "was left" with "had left."

The second sentence when the guided clause lacks a predicate verb, from a to b is a prepositional phrase, which can be regarded as a predicate and can be added as a conjunctive verb.

When I arrived at the bus station, the bus had already left

None of them are right. The main reason may be that the parts of speech of the words are not clear.

The "was left" in the first sentence is a verb + predicate structure, and the verb cannot be a predicate.

It can be changed to: when i arrived at the bus station, number 20 bus was not there.

The "you from a to b" sentence in the second sentence is missing a predicate verb.

It can be changed to: what did you say when you was from a to b?

Or turn it into a word: what did you say during from a to b?

The first sentence is not in the right voice, was left is the passive voice, and it is correct to directly use left or had left to form the active voice. The second sentence doesn't know what you want to express, the clause is incorrect, and the predicate is missing, if it is fromatob, then you can add were

root, pinyin: [gēn] Interpretation: The part of the stem of a higher plant that grows in the soil. The base of the object is connected to something else. The origin of things. Thorough. basis, as the fundamental. A measure word that refers to something that is long strips.

I think that's how it's written:

when i arrived at the bus station，number 20 bus had left.

make

upone's

MIND is a fixed collocation.

However, although there is a start

on.

This phrase, here on

is a preposition that comes down to the latter and serves as a place adverbial clause.

Analysis: start

on is a transitive verb, followed by an object, and the object is obviously missing here if start

on the hold, then the adverbial that follows.

theoutside

ofyour

houseearly

nextweek

is redundant and therefore does not hold.

So, the answer is.

ontheoutside

ofthehouse