Задача 1
Условие (кратко)
По картинкам упражнений 1 и 2 составить предложения по образцу It's a cap. It's an ant.
Решение
Перед словом, которое начинается с согласного звука, ставим a, перед гласным звуком — an.
С a: It's a ball. It's a cat. It's a doll. It's a fox. It's a girl. It's a hat. It's a hand. It's a book. It's a cap. It's a flag. It's a dog.
С an: It's an apple. It's an egg. It's an ant. It's an envelope.
garlic (чеснок) обычно не считают по штукам, поэтому говорят без артикля: It's garlic.
Ответ
It's an apple. It's a ball. It's a cat. It's a doll. It's an egg. It's a fox. It's a girl. It's a hat. It's a hand. It's a book. It's an ant. It's a cap. It's an envelope. It's a flag. It's a dog. It's garlic.
Почему так
Артикль an ставится перед словом на гласный звук, a — перед словом на согласный.
Подробнее — в теме «Неопределённый артикль a/an».