989.The companies are working together to create ____ they hope will be the best means of transport in the 21st century.
A.which
B.that
C.what
D.who
990.The last time we had great fun was _____ we were visiting the Water Park.
A.where
B.how
C.when
D.why
989.答案是C;该句中they hope是插入语，而实际上create后接宾语从句，但缺少连接词，并且该连接词在从句中充当主语，故选what。
990.答案是C;由the last time得知，此题与时间有关，故用when引导表语从句。
