Answer:
1. If you cannot see without your glasses, you should not be driving.
2. Our flight has been delayed because of the thunderstorm.
3. Though I don’t doubt his sincerity, I cannot agree with his position on that issue.
Step-by-step explanation:
A complex sentence contains an independent clause along with one or more dependent clauses. Moreover, these sentences/ clauses are joined or linked by appropriate conjunctions.
As given in the rules in the question, if the independent clause comes before the dependent clause, then the use of a comma is unnecessary whereas it is vice versa for when a dependent clause comes first.
Therefore, the given sentences will be punctuated as follows-
1. If you cannot see without your glasses, you should not be driving. (Comma is used as the dependent clause comes before the independent clause)
2. Our flight has been delayed because of the thunderstorm. (The independent clause comes before the dependent clause, so the comma is omitted)
3. Though I don’t doubt his sincerity, I cannot agree with his position on that issue. (Comma is used as the dependent clause comes before the independent clause)