1. The correct answer is A: "I saw Tom while he and his family were riding a jeep to the top of Langbiang Mountain."

Explanation: In this sentence, the correct verb tense is the past simple ("I saw") to indicate the action of seeing Tom, and the past continuous ("were riding") for the action happening simultaneously when you saw Tom.

1. The correct answer is D: "An suggested taking a bus to Aeon mall instead of going there by motorbike."

Explanation: After the verb "suggest," we use the gerund form (taking, going) instead of the infinitive.

1. The correct answer is C: "The more you practise, the fewer mistakes you'll make."

Explanation: In the comparative structure "The more... the more," we use "fewer" (not "few") to modify countable nouns like "mistakes."

1. The correct answer is D: "This is the first time Alice has tried Com Lang Vong in Viet Nam."

Explanation: For the first time, we use the present perfect tense ("has tried") to indicate an experience that has occurred at an unspecified time in the past and is still relevant now.