Roger Woodham replies:'by' and 'from'

'by' with passive clauses

In passive constructions, as in your example, the agent of the action is always introduced with the prepostion by, so the first one is correct.

We could turn the passive sentence into an active sentence if we wanted to use from and say:

But for all passive clauses we need to use by when introducing the person or thing responsible for the action:

The only exception to this is when we are talking about the tools used for the operation rather than the agent bringing about the action.

When we talk about the tools used for an action we say with rather then by.

Compare the following:

'by' to express time

By is used to indicate time up to a particular point:

by or near?

By also means very close to.

For example:

'by' in common phrases

By is used in a number of common phrases.

Note the following:

Note, however, if we put a determiner in front of the noun, it is no longer a set phrase and the preposition changes.

Compare the following:

from or since?

The preposition from indicates the starting point of an action. It is often used with to or till which indicates the finishing time of the action:

Note that since is used with the present perfect or past perfect tense to indicate the starting point of the action. With other tenses we normally use from.

Compare the following: