The betaine will collapse to the alkene only when these two functions are eclipsed.只有當(dāng)這兩個(gè)基團(tuán)移至重迭位置時(shí)碘鹽才能裂解為烯烴.The gramophone had been eclipsed by new technology such as the compact disc.激光唱片等新技術(shù)使留聲機(jī)黯然失色。Our happiness was s...