【单选题】Though he is very intelligent, he is ______ rather modest.
【单选题】为了提高雌性乳牛出生的比例,可在体外将携带X染色体和Y染色体的镜子分离开,进行人工授精。最好的分离方法使
【单选题】The man dressed _____ jeans is an expert _____ unlocking doors and he can open a door ______ difficulty.
【单选题】为了提高雌性乳牛出生的比例,可在体外将携带X染色体和Y染色体的精子分离开,进行人工授精。最好的分离方法是
【简答题】He looks rather (elder) ________ with grey hair.
【单选题】-- Do you think we should accept that offer? -- Yes, we should, for we _____ such bad luck up till now, and time out. [ ]
D.
have had, has been run
【单选题】半合成抗生素是
A.
半人工合成的新抗生素与天然抗生素作用完全不同
B.
人工合成的新抗生素保留天然抗生素优点,改其缺点
C.
保留天然抗生素主要结构,人工更换侧链所得产品