They wrote a letter of thanks to ________ had helped them.
A、whoD
暂无解析
翻译：WeadvisedyouinourletterofDec.1,thatwewouldliketoplaceatrialorderwithyoufor50piecesFlyingPigeonBicycles.
They________extensiveandpossiblydangerousactualflighttraining.
ThetheoryoflanguageunderlyingtheGrammar-TranslationMethodwasderivedfrom_____Linguistics.
Sincethepremiumvarieswiththescopeof____extrapremiumisforbuyer'saccount,shouldadditionalsiskecovered?()
Itisdifficulttounderstandthiskindof_______calculation.
