Relative clauses without relative pronouns: แบบฝึกหัด

In which of the following sentences can the relative pronoun be omitted?

Relative pronouns can often be omitted in defining relative clauses when they function as the object of the clause. In which of the following sentences has the relative pronoun been correctly omitted?

Consider the following formal sentence structure:

"The research project, for which the students gathered data from multiple sources, was highly successful."

If we want to rewrite this as a relative clause without a relative pronoun while maintaining a standard (though less formal) meaning, which version is correct?

In which of the following sentences is the relative pronoun who or that acting as the subject, meaning it cannot be omitted?

When omitting a relative pronoun from a clause that contains a preposition, what happens to the preposition?
(Example: The man with whom I was talking...)

Rewrite the following sentence by omitting the relative pronoun:

The textbook that the teacher recommended for our history project is now available in the library.<\/i><\/p>

Explain whether the relative pronoun can be omitted in the following sentence and why:

The girl who is standing by the school gate is my cousin.

Analyze the following sentence: "The research students conducted led to a major medical breakthrough."

1. Identify the relative clause without a relative pronoun.
2. Rewrite the sentence including the relative pronoun.
3. Explain the grammatical function of the omitted pronoun.

Read the following short paragraph and complete the tasks below:

The ancient scroll (which) the archeologist found in the desert was written in a lost language. The translation process (that) the experts started last week is proving to be very difficult.

a) Rewrite both sentences by omitting the relative pronouns in brackets.
b) Explain the grammatical rule that allows these relative pronouns to be omitted in these specific sentences.
c) In the sentence "The archeologist who discovered the scroll was famous," can the underlined word be omitted? Why or why not?