Question 13:

• Error: The verb tense is incorrect.
• Correction: C. takes should be take.
  • Correct sentence: We will get lost unless we take a map.

Question 14:

• Error: The verb tense in the if-clause and the main clause are inconsistent.
• Correction: D. pleased should be will be pleased.
  • Correct sentence: If the little girl knew how to do it, her mother will be pleased.

Question 15:

• Error: The verb tense in the if-clause is incorrect.
• Correction: A. will be should be there is.
  • Correct sentence: If there is too much exhaust fume in the air, our breathing will be badly affected.

Question 16:

• No error.

Question 17:

• Error: The verb tense in the if-clause and the main clause are inconsistent.
• Correction: C. had should be have.
  • Correct sentence: If you really want to get good grades, you have to study hard.

Question 18:

• Error: The verb tense in the if-clause is incorrect.
• Correction: A. will stay should be stay.
  • Correct sentence: If you stay in bed and take enough medicine, the flu will certainly disappear in three days.

Question 19:

• Error: The verb tense in the if-clause is incorrect.
• Correction: A. will burn should be burn.
  • Correct sentence: If we burn trash to reduce the amount of garbage, we will certainly pollute the air.

Question 20:

• Error: The verb tense in the if-clause and the main clause are inconsistent.
• Correction: C. had should be has.
  • Correct sentence: Nam'll get up early if he has an alarm clock.

Question 21:

• Error: The verb tense in the if-clause is incorrect.
• Correction: A. went should be go.
  • Correct sentence: If you go to his office after 10 a.m., you will see him.

Question 22:

• No error.

Question 13: C. takes should be take. The correct conditional sentence structure is: If + present simple, will + simple present.

Question 14: D. pleased should be pleased. The correct conditional sentence structure is: If + simple past, would + simple present.

Question 15: A. will be should be were. The correct conditional sentence structure is: If + simple past, would + simple present.

Question 16: A. won’t should be don't. The correct conditional sentence structure is: If + simple present, will + simple present.

Question 17: C. had should be have. The correct conditional sentence structure is: If + simple present, will + simple present.

Question 18: A. will stay should be stay. The correct conditional sentence structure is: If + simple present, will + simple present.

Question 19: A. will burn should be burn. The correct conditional sentence structure is: If + simple present, will + simple present.

Question 20: C. had should be have. The correct conditional sentence structure is: If + simple present, will + simple present.

Question 21: A. went should be go. The correct conditional sentence structure is: If + simple present, will + simple present.

Question 22: C. can not should be can't. The correct conditional sentence structure is: If + simple present, will + simple present.