She staayed at home because he mother was sick.

Because of her sick mother, she stayed at home.

I like him because his father in kind to me.

Because of his kind father, I like him.

I couldn't do the test because it was difficult.

Because of the difficult test, I couldn't do it.

Although English gmamar is difficult, we like to study it

In spite of difficult English grammar, we like to study it.

She stayed at home because he mother was sick.

⇒ Because of her mother's sickness, she stayed at home

I like him because his father in kind to me..

⇒Because of his father's kindness, I like him.

I couldn't do the test because it was difficult.

⇒ Because of the tests' difficult, I couldn't do it.

Although engsh gmamar is difficult, we like to study it.

⇒ In spite of the difficult of E grammar, we like to study it.