=>

1. It is dangerous to let children play in the kitchen.

It is not safe to let children play in the kitchen.

2. It is not safe to put a knife into an electrical socket.

It is dangerous to put a knife into an electrical socket.

3. It is unhealthy to eat too much fast food.

It is not healthy to eat too much fast food.

Dangerous : nguy hiểm >< safe : an toàn

Unhealthy : không lành mạnh, khỏe mạnh >< healthy : lành mạnh, khỏe mạnh

$1$ `:` It is dangerous to let children play in the kitchen.

`->` It is not safe to let children play in the kitchen.

$2$ `:` It is not safe to put a knife into an electrical socket.

`->` It is dangerous to put a knife into an electrical socket.

$3$ `:` It is unhealthy to eat too much fast food.

`->` It is not healthy to eat too much fast food.

`=>` Dangerous `:` Nguy hiểm >< Safe `:` An toàn

`=>` Unhealthy `:` Không lành mạnh, khỏe mạnh >< Healthy `:` Lành mạnh, khỏe mạnh