Question: Mrs. Jones _____ with us since last year.
Correct Answer: has been studying
This question tests the present perfect continuous tense, which is used for actions that started in the past and continue to the present. "Since last year" indicates duration, making this the correct choice.

Incorrect Answers:
- studies - Simple present tense doesn't show duration from past to present.
- studied - Simple past tense doesn't connect the action to the present.
- is studying - Present continuous doesn't show the action started in the past.