医用化学杂志曾报道，有一种功能高分子材料为聚乙交酯纤维材料C，用这种功能高分子材料制成手术缝合线比天然高分子材料的肠线好．它的合成过程如图所示：

已知向量a＝(2,4,5)，b＝(3，x，y)分别是直线l₁、l₂的方向向量，若l₁∥l₂，则 (   )

清朝学者万斯大说：“古之时，诸候之嫡长子为世子，嗣为诸候，其余支庶之后，族类繁多，惧其散而无统也，因制为大宗小宗之法。”材料主要说明了（     ）

下列各句中，划线的词语运用正确的一项是  (　　)

阅读下列短文，从每小题的三个选项中选出最佳选项。

     Hello, I'm Linda. I have a garden. There are some plants and flowers in my garden. I like smelling flowers in it. Look at this small plant. It's a gift from my grandmother. It's for Children's Day. I like it very much. It is small and short. It has two small leaves. I water it every day. The plant grows and grows. Now it is big. It has more(更多) leaves. Now it has three pink flowers. They are beautiful. I like these beautiful flowers very much.