She gave birth to a baby in the maternity hospital.

My younger brother is good at addition in arithmetic.

This silkworm produces beautiful silk.

This lemon is sour.

We cannot live without oxygen.

He calculated the area of the triangle.

He is good at solving trigonometry problems.

He is good at arithmetic.

A day without seeing her feels like an eternity of waiting impatiently.

I make a sandwich every morning.