Question 10: Mike isn’t on the phone, ……….. makes it difficult to contact him.

Knowledge: Relative clauses

Explain:

In a relative clause we can use “which” to replace an entire clause before it, before “which” has a comma.

whom: instead of the noun who refers to a person; act as an object in a relative clause

who: replaces a noun indicating a person; play the role of subject and object in relative clauses

that: don’t use “that” before it has a comma

Mike doesn’t answer the phone, it’s very difficult to contact him.