Here are the best options to complete each sentence based on the provided text:

**I. Choose the best option to complete each sentence:**

Câu 11: Ha Long Bay is Vietnam’s best **A. natural wonder**.

Câu 12: Cuc Phuong **C. forest** is in Ninh Binh.

Câu 13: A **B. sleeping bag** is very useful when you go camping overnight.

Câu 14: Children receive **C. lucky money** in red envelopes at Tet.

Câu 15: At Tet, we **C. decorate** our homes with trees and flowers.

Câu 16: I am **B. the tallest** (if comparing with siblings) or **C. taller** (if comparing with someone else).

Câu 17: A girl **A. reads** her book now.

Câu 18: My mother is a good cook. She often **A. cooking** special food for Tet (correct form is "cooks").

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**II. Underline and correct the mistake in each sentence:**

Câu 19: My mother is **cooking in the chicken now** (should be "cooking chicken now").

Câu 20: We must **wearing** uniform from Monday to Saturday (should be "wear").

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Let me know if you need further assistance!