Giúp mình 3 câu này với ạ

11. (A) competitive

Explanation: The sentence states that Verizon's new mobile phone has proven to be the most _______ model on the market due to its numerous useful application programs. The word "competitive" fits in this context as it means having the ability to compete effectively with other models on the market.

12. (A) will begin

Explanation: The sentence states that now that the final terms of the contract have been confirmed, Mr. Jackson _______ the construction project before the end of this month. The phrase "will begin" is the correct choice as it indicates a future action that will take place after the confirmation of the contract terms.

13. (C) originally

Explanation: The sentence states that the unexpected operating complexity was more serious than anticipated. The word "originally" fits in this context as it means in the beginning or at first, indicating that the level of complexity was greater than initially expected.