These questions ask you to separate the doer from a tool or material, decide whether the doer belongs in the sentence at all, and complete the required passive form. The safest method is to identify each role before choosing a preposition or verb phrase.
Identify the role, then build the passive
Start by asking what caused or performed the action and what was merely used. The agent is the participant presented as responsible for the event, so an expressed agent follows by. A hand-controlled tool or a substance used in the process follows with. This is a role distinction, not simply a human-versus-nonhuman test: a nonhuman force can be presented as a cause with by, but an object explicitly described as a tool remains an instrument with with.
| Signal in the sentence | What to do |
|---|---|
| A person, group or cause is responsible for the event | Introduce that participant with by if naming it adds useful information. |
| A tool is controlled or used to perform the action | Introduce the tool with with. |
| A substance is described as the material used in the process | Introduce the material with with. |
| The doer is unknown, predictable from the routine, or irrelevant to the topic | Leave the agent phrase out and keep the receiver as the passive subject. |
After settling the roles, check the verb phrase independently. A past simple be-passive uses was or were, chosen to agree with the passive subject, followed by the past participle. A get-passive can be standard in informal English, but it does not satisfy an instruction that specifically asks for the be-passive. This final check prevents a correct preposition from hiding an incomplete or wrongly formed passive.
Avoid these traps
- By can look tempting after any passive because it often introduces what comes next. Reject it when the sentence presents that noun as a hand-controlled tool or material used by someone else; the required relationship is then expressed with with.
- With can seem like a general link between the action and another participant. It is wrong when that participant actually carried out the work, because an acting person or group is an agent and belongs after by.
- An agent phrase may be grammatically possible but communicatively pointless. If the doer is unknown, obvious from an everyday routine, or unimportant to the topic, naming a vague or predictable doer weakens the intended receiver focus; stop the passive after the participle and any useful circumstances.
- A sentence can identify roles correctly and still fail to form the requested passive. Do not replace be plus participle with an active clause or with be plus an -ing form: the first changes the receiver focus, while the second presents the subject as performing an ongoing action.
Try it
Use the be-passive form of the verb in brackets in the past simple. A craft worker controlled a fine brush as the instrument: the cedar panel ___ with the brush during yesterday's workshop. (decorate)
Use the be-passive form of the verb in brackets in the past simple. A blue ribbon is the topic, but the person responsible is unknown and must be omitted: it ___ to the garden gate overnight. (tie)
Select all passive sentences that treat the named substance as a material and the named person as an agent.
- The linen was coloured by a plant-based dye used as the material.
- The linen was coloured with a plant-based dye used as the material.
- The coastal map was drawn with a cartographer acting as the agent.
- The coastal map was drawn by a cartographer acting as the agent.