酶的负协同效应使酶的（）对（）不敏感。
参考答案：反应速度；底物浓度
．—Wow! And what does your brother do?
—He’s a painter．He ______ in France this month．He has an exhibition there．
A．works
B．worked
C．has worked
D．is working
—Hello! Who’s this?
—
A．I’m Tom. B．That’s Tom. C．This is Tom.
