用电磁波作为传热介质，波长越长，单位能量越（）。
参考答案：低
Over two hundred years ________ since the United States ________in 1776[ ]
A. have passed; founded
B. has passed; were founded
C. have passed; was founded
D. has passed; was founded
细胞水肿与脂肪变性最易发生在：（）
A.肺、脾、肾
B.心、肝、肾
C.肺、脾、心
D.心、肝、脾
E.肝、肾、脾
