The _______ work continued for more than a week but there was still no sign of the missing boy.
A、researchB
暫無解析
Inordertoincreaseouroutput,weneedtoimportmoreproduction_______.
The engineers in this lab spent several weeks _______their plans for the new bicycle.
Itisnot---_______formetoreturnallthebookstothelibrarynowbecauseIstillneedsomeofthemformyresearch.
Whentravelingaloneinthemountains,you’dbettertakea_______withyouincaseyougetlost.
Manykindsofanimalsarebelievedtohave_________fromtheearth
