Writing a song is not as difficult and complicated as it seems.
创作歌曲并非像看起来的那样复杂艰难。
Efficient separations of platinum metals from each other are quite difficult and complicated.
铂族元素的相互分离相当困难和复杂。
Efficient separations of platinum metals from each other are quite difficult and complicated.
铂族元素的相互分离相当困难和复杂。
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