Youngerchildrenarecurious________howthingswork，andmanyofthemwanttotakeaparteverythingwithintheirreach.
B
译文：小孩子对事物是如何组成的很好奇，一些孩子总是想把他们够得到的东西都拆开。此题考查短语搭配， be curious about 对…好奇。
Thisisanimportantproblem_______toofewsocialscientistshaveresearched.
Iwaswritingareportlastnight;________Iwouldnothavestayeduplate.
Accordingtothe"principles-and-parameters"theory,"principles"refertohighlyabstractpropertiesofgrammarwhichareappliedtolanguageingeneralandwhichgeneratephrasesandatthesametimerestrainthepowerofMovea,while"parameters"allowgeneralprinciplestooperateincertainrestrictedways,accordingtowhichparticulargrammarsofnaturallanguagesvary.
Johnsonwas________unknownbeforerunningforthepresidency.