Sure! Here are the corrections for each underlined part:

1. **(A)** saying → **(A)** says
**(B)** Literature → **(B)** Literature
**(C)** built → **(C)** built
**(D)** 11th → **(D)** 11th

**Corrected Sentence**: It **says** that the Temple of Literature was **built** in the 11th century.

2. **(A)** suggest → **(A)** suggest
**(B)** must → **(B)** should
**(C)** book → **(C)** a

**Corrected Sentence**: They **suggest** that we **should** book a hotel by the Perfume River.

3. **(A)** have → **(A)** has
**(B)** claimed → **(B)** claimed
**(C)** are → **(C)** are

**Corrected Sentence**: Many people **has** claimed that the show tickets **are** too expensive.

4. **(A)** suggest → **(A)** suggest
**(B)** in → **(B)** at
**(C)** four → **(C)** four
**(D)** this afternoon → **(D)** this afternoon

**Corrected Sentence**: We **suggest** to cycle **at** the castle **at** four o'clock this afternoon.

5. **(A)** well → **(A)** good
**(B)** to → **(B)** to
**(C)** as → **(C)** because

**Corrected Sentence**: It's **good** worth to go to Ha Long Bay **because** it is very picturesque.

Here’s the corrected version of the sentences:

1. It **says** that the Temple of Literature was **built** in the 11th century.
2. They **suggest** that we **should** book **a** hotel by the Perfume River.
3. Many people **have** claimed that the show tickets **are** too expensive.
4. We **suggest** to cycle **at** the castle **at** four o'clock this afternoon.
5. It's **good** worth to go to Ha Long Bay **because** it is very picturesque.