1. Jane isn't old enough to stay at home alone 

Cấu trúc enough dạng khẳng định

S + tobe not + adj + enough + (for SB) + to V-inf

S + don’t/doesn’t/didn’t +V + adv + enough + (for SB) + to V-inf

2. Sitting in front of a computer all day can cause health problems. 

cause sb/sth to do sth

3. Nowaydays, teenagers rely on technology more than in the past

Nowadays là một trạng từ có nghĩa 'ngày nay', 'tại thời điểm hiện tại'.

4. Life in the countryside has changed a lot over the past  ten years.

5. There is a large round wooden table in the kitchen

THERE IS + Danh từ số ít + Trạng ngữ nếu có

1.Jane is not old enough to stay at home alone.

2.Sitting in front of a computer all day can cause health problems.

3.Nowaydays, teenagers rely on technology more than in the past.

4. Life in the countryside has changed a lot over the past  ten years.

5. There was/is a large round wooden table in the kitchen.