题目

构成生物大分子的基本骨架是（ ） A．磷脂 B．碳链 C．单糖 D．氨基酸 答案：解：组成细胞的基本元素有：C、H、O、N，其中C是组成细胞的最基本元素，因为碳链是生物大分子的基本骨架．因此构成生物大分子基本骨架的元素是C． 故选：B．根据汉语提示补全句子。1. I want to go to Guilin on my ____________ (旅行). 2. There are about ____________ ____________ (三千) books in our library.3. Which one is ____________ (更快) , bus or train?  I think train is. 4. ____________ ____________ (多远) is it from hospital to your school?  Three kilometres. 5. When does your bus ____________ (到达)?  At about 6: 00 in the morning tomorrow.