正确答案: B

①④

题目：多基因遗传病是一类在人群中发病率较高的遗传病。以下疾病属于多基因遗传病的是①哮喘病 ②21三体综合征 ③抗维生素D佝偻病 ④青少年型糖尿病

解析：21三体综合征是染色体异常遗传病，抗维生素D佝偻病是X染色体上显性遗传病，哮喘病和青少年型糖尿病是多基因遗传病。

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学习资料的答案和解析：

[单选题]Now that we’ve discussed our problem, are people happy with the decisions _______?

takenD .to take

[单选题]CHonesty comes in many forms. First there’s self-honesty. Is what people see the real article or do you appear through smoke and mirrors? I find that if I try to be something I’m not , I feel unsure of myself and take out a part from my PBA(personal bank account ).I love how singer Judy Garland put it, “Always be a first-class version(版本) of yourself , instead of a second-class version of somebody else .”

to be unreal

[单选题]花柄长短不等，下部分花柄较长，越向上部，花柄越短，各花排在同一平面上称( )。

伞房花序

[单选题]侧根是维管形成层产生的。( )

错误

[单选题]由卵细胞直接发育成胚称( )。

孤雌生殖