Готовые предложения (по 4 варианта):
They didn't go out because it was snowing. / They didn't go out as it was snowing. / They didn't go out because of the snow. / They didn't go out due to the snow.
She didn't enjoy the party because it was crowded. / She didn't enjoy the party as it was crowded. / She didn't enjoy the party because of the crowd. / She didn't enjoy the party due to the crowd.
Ann couldn't walk because her leg was broken. / Ann couldn't walk as her leg was broken. / Ann couldn't walk because of a broken leg. / Ann couldn't walk due to a broken leg.
He couldn't sleep because it was noisy. / He couldn't sleep as there was a lot of noise. / He couldn't sleep because of the noise. / He couldn't sleep due to the noise.
The road was closed because there had been an accident. / The road was closed as there had been an accident. / The road was closed because of an accident. / The road was closed due to an accident.
The trains were cancelled because there was a strike. / The trains were cancelled as there was a strike. / The trains were cancelled because of the strike. / The trains were cancelled due to the strike.
He didn't go to school because he was ill. / He didn't go to school as he was ill. / He didn't go to school because of his illness. / He didn't go to school due to illness.
He gave up his job because his health was poor. / He gave up his job as his health was poor. / He gave up his job because of poor health. / He gave up his job due to poor health.
Схема: because/as + предложение, because of/due to + существительное.