The exchange of substituents between 3,5-dibromo-1,2,4,3,5-trithiadiborolane ( 1 ) and 1,2,3-trimethyl-1,3,2-diazaborolidine ( 2 ) proceeds via formation of adducts as indicated by tetracoordinated boron atoms but definite products could not be isolated. However, a well defined ...
"Fairyland" is perhaps the only word to choose.答案(1)fascinating.考查形容词。句意:中国西南部的四川省以其众多迷人的自然奇观而闻名,几个世纪以来吸引了数百万游客。此处用形容词作定语修饰名词natural wonders,表示"迷人的",故填fascinating。(2)travelers.考查可数名词的复数。句意:中国...