A:主要存在于微生物中
B:一种限制酶可以识别多种特定的核苷酸序列
C:一种限制酶能在不同的切点上切割DNA分子
D:其化学本质是DNA
(____)1. Let me clean the window.
(____)2. Look! The bird is on the light.
(____)3. There isa picture on the wall.
(____)4. The book is near the computer.
(____)5. The bag is on the chair.
A. B. C.
D. E.
世界上华人、华侨最集中的地区是( )