Which of the following is a complete sentence?

a. although henry was unusually tall.
b. since she was hungry, she had a snack.
c. even when the temperatures improved.
d. because i had not slept for two nights

1- cleans/ tidies up

2- were

3-would be

4- had known

5-takes

6-must be/ have to be/should be

either online or traditional classroom can work for students. which is better will depend on students and teacher. students may have trouble following a lesson in classroom while they can study at their own pace online. other students may have trouble staying focus on their own in online classes. teachers are more used to classroom teaching but they may also be more worry about their jobs teaching online classes and work harder.