【题目】_______ about wild plants that they decided to make a trip to Brazil for further research.
A.So curious the couple was
B.So curious were the couple
C.How curious the couple were
D.The couple was such curious

【答案】B
【解析】考查 so...that...引导结果状语从句，且 so...放于句首时，句子部分倒装。