Since the nineteen nineties , education has been required for all south africans from age seven to fifteen .
从二十世纪九十年代起，南非所有7到15岁儿童必须接受教育。
Khodorkovsky 's arrest , in 2003 , followed by two ludicrous show trials and imprisonment in the far east , was putin 's most blatant demonstration of power to the class of oligarchs that had made its fortune in the legal vacuum of the nineties .
In the nineteen nineties , gebisa ejeta and another purdue researcher , larry butler , identified the complex relationships between striga and sorghum plants .
