Mike is my friend. _____ Jenny's brother. [ ]
A. He
B. He's
C. His
D. She's
答案:B
定向辐射强度是指单位时间,(),()内的辐射能量。
舌下含片的吸收窗是()
A.口腔黏膜
B.舌下黏膜
C.呼吸道黏膜
D.牙龈黏膜
E.咽喉黏膜