问题补充：
单选题ScientistsbelievenativeAmericansarrivedbycrossingthelandbridgethatconnectedSiberia(西伯利亚)andmorethan10，000yearsago．A.this is AlaskaB.Alaska is nowC.is now AlaskaD.what is now Alaska
答案：
D解析这题考查what引导的宾语从句：connect后面应该是宾语从句，从句中缺少的是主语，所以用what引导。选D.
