上海新東方四六級教研組

    87. Medical researchers are painfully aware that there are many problems (that/which) they haven't found solution to (他們至今還沒有答案)。 
    88. What most parents concern (大多數(shù)父母所關(guān)心的) is proving the best education possible for their children. 
    89. You'd better take a sweater with you in case it (should) turn cold.（以防天氣變冷） 
    90. Through the project, many people have received training and decided to launch their own enterprose （決定自己創(chuàng)業(yè)）。 
    91. the anti-virus agent was not known until a doctor discovered it by chance.（直到一名醫(yī)生偶然發(fā)現(xiàn)了它）。