Although these molecules allow radiation at visible wavelengths,where most of the energy of sunlight is concentrated,to pass through,they absorb some of the longer-wavelength,infrared emissions radiated from the Earth’s surface,radiation that would otherwise be transmitted back into space. (4)
解释:前面的分句中有一个不算很长的插入语,但是因为它插入的位置正好在固定搭配allow something to do somthing中间,将allow和to分得很远,所以读起来让人感觉很不舒服。后面的分句中的最后一行radiation that would otherwise be transmitted back into space是其前面的infrared emissions的同位语。其中的otherwise是副词作状语,表示如果后面的分句所说的they absorb some of the longer-waverlength, infrared emissions不发生时的后果。
训练:Although these molecules allow radiation at visible wavelengths, where most of the energy of sunlight is concentrated, to pass through, they absorb some of the longer-wavelength, infrared emissions radiated from the Earth's surface, radiation that would otherwise be transmitted back into space.