非连续性噪声水平：屋内90dB，屋外（）dB。
A.95
B.100
C.110
D.120
参考答案：D
It’s difficult _____ us to remember new words.
A．of
B．to
C．for
D．on
A restaurant orders 150 kg of pumpkins from the farmer’s market. The farmer fills the order with 23 pumpkins. The average mass of the first 20 pumpkins is 6.5 kg. What must be the minimum average mass of the remaining 3 pumpkins to fill the order ？（）
A. 5.5 kg
B. 5.67 kg
C. 6.67 kg
D. 7 kg
E. 11.5 kg
