问题

The problem will appear_____ a different welfare system will be created. [ ]

A: unless
B: whether
C: until
D: if

正确答案是：

同类题型

Eating is so important to Chinese ______ we have the term"food culture" But recent reports have the publicworried about ______ is on their tables

It’sapleasuretowatchthefaceofa__________baby.[ ]

ory showed marriage between people of differentraces ,_____ was against the law at that time

So far this year we _______ a fall in house prices by between 5 and 10 percent

My favorite ________ is summer. I can swim with my friends.