Answer:
If we watch that, I'll fall asleep.
Step-by-step explanation:
Commas are helpful when combining independent clauses with dependent clauses in the same sentence.
First, define an independent and a dependent clause is. An independent clause is a clause that has 3 important parts: a verb, subject, and complete thought. Dependent clauses are similar; however, they have no complete thought. They still have a subject and verb, but they cannot stand on their own.
A helpful way to remember the difference is that an independent clause is independent and does not require any help. On the other hand, a dependent clause depends on another clause to make it a complete sentence.
Next, identify the different clauses within the sentence given. There are 2 clauses, one independent and one dependent. The clause, "If we watch that" is a dependent clause. "Watch" is the verb and "that" is the subject; however, because of the word "if" there is no complete thought. The clause, "I'll fall asleep" is an independent clause. "I" is the subject and "fall asleep" is the verb phrase. This clause also expresses a complete thought.
Finally, connect these clauses. A dependent clause can be connected to an independent clause with a simple comma. So, the final answer is "If we watch that, I'll fall asleep."