We all know that we’ll meet all kinds of difficulties in our lives in the future. We should learn to be ________ any challenge!
A:confident enough to take on
B:active enough to take up
C:enough careful to take try on
D:enough patient to try out
They hope to stand the top of the mountains one day.
下面四个单位中,哪个是用来表示声音强弱的单位( )
预防肺结核的方法是按时接种____ ,使人体内产生抵抗结核杆菌的抗体,人体对肺结核就能产生免疫力,这种免疫属于____ (填“非特异性”或“特异性”)免疫。