例1：Elsewhere,
rice experts in the philippines are producing a plant with few _____
stems and more seeds.
解析：and要连接两个对称结构，此处应该为比较级：fewer stems and more seeds。
例2：Their fields yield twice as much corn this year than they did _______
last year after adopting the advanced technology.
解析：此处是as…as…结构，故应该把than 改为as。
拓展：在比较结构中，一般用than来连接，但有些词用to如：superior/inferior/senior/junior.或者as…as
例3：The climate in the coastal cities is much warmer than in the _______
interior cities．
解析：句中用于比较的两个部分是气候而不是地区。故应在在than与 in之间应加指示代词that。
