Today, most of the difficult and dangerous work is done by computers and other powerful machines. In the past conditions of (3) were not as comfortable as they are now.

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Today, most of the difficult and dangerous work is done by computers and other powerful machines. In the past conditions of (3) ______ were not as comfortable as they are now.

live

livable

lively

living

Giải thích

Đáp án đúng là: D

Sau giới từ cần Ving.

Dịch: Trong quá khứ điều kiện sống không được thoải mái như bây giờ.