以下属于高新产业区与所在国家对应正确的是（  ）

Tom is from London. He's now in Beijing with his parents. His father and mother teach in a school. He studies in a middle school. The school is four miles from his home. He usually walks to school. He says, "It can make me healthy." Sometimes when it rains, he takes a bus. He's never late, and he's always the first one to get to school. He's good at all his subjects, and often helps us with our English. We all love him very much.

单子叶植物种子的子叶的作用是（ ）。