in 1990s还是in the 1990s

in the 1990s'还是in the 1990's in 1990s还是in the 1990s in the 1950s 还是in 1950sin the 1950's 还是 in 1950's in early 1990s还是in the early 1900s?到底加不加这个the? in the 1950s还是in 1950s IN 1960S 还是IN THE 1960S in the 1970s=in the 1970's还是=in 1970's 是in1980s还是in the 1980s What's the weather like in winter in Beijing?还是What's the weather like in Beiing in winter? 是in the barber's 还是at barber's 在90年代是 in 90s 还是in the 90s?那么,in the 1620s 是什么意思? In this survey,people who was born in 1990s is the study subject.In this survey,people who was born in 1990s is the study subject.还是In this survey,people who was born in 1990s are the study subjects.还是In this survey,people who were born in 19 in the 1990s,in the 1990's和in 1990的区别 in the 1990s 、 in 1991s 、 in the 1991s、 in 1990都有什么含义? in the cat,s In the stationary’s in 1950s 与in the 1950s有什么区别?in 1950s是表示1950----1959还是1940---1949?in the 1950s呢? At the fashion show,they wore different clothes ( ) 填in the 1990s还是from the 1990s 说明理