The verb should agree with its subject in number and person.

Repeated words are often left out.

• Twelve rioters have been sentenced and five acquitted. (= Twelve rioters have been sentenced and five have been acquitted.)

Note that this omission is only possible in parallel structures.

• Incorrect: Ten new candidates have been appointed, and five resigned.
• Correct: Ten new candidates have been appointed, and five have resigned.

Here the verb in the first clause is in the passive voice and the verb in the second clause is in the active voice.

Repeated words cannot be omitted in such situations.

Lay and lie

These verbs are often confused.

The verb lay is transitive. It should be followed by an object.

• Lay the books on the table.
• I have laid the table.

Laid is the past and past participle form of lay.

The verb lie is intransitive. It cannot have an object.

• Let me lie here.
• He lay under a tree. (Here ‘lay’ is the past simple form of the verb ‘lie’.)
• He has lain on the sofa. (Lain is the past participle form of the verb ‘lie’.)

A participle should have a proper reference in the sentence. The following sentence is wrong.

• Incorrect: Standing at the gate, a scorpion stung him.

This sentence seems to suggest that it was the scorpion that was standing at the gate.

It has to be rewritten as follows:

• Standing at the gate, he was stung by a scorpion. OR
• While he was standing at the gate, he was stung by a scorpion.