火鸡的性别决定方式是ZW型(♀ZW,♂ZZ)。曾有人发现少数雌火鸡(ZW)的卵细

题型:选择题

问题:

火鸡的性别决定方式是ZW型(♀ZW,♂ZZ)。曾有人发现少数雌火鸡(ZW)的卵细胞未与精子结合,也可以发育成二倍体后代。遗传学家推测,该现象产生的原因可能是:卵细胞与其同时产生的三个极体之一结合,形成二倍体后代(WW的胚胎不能存活)。若该推测成立,理论上这种方式产生后代的雌雄比例是[ ]

A.雌:雄=1:1

B.雌:雄=1:2

C.雌:雄=3:1

D.雌:雄=4:1

考点:性染色体与性别遗传基因型和表现型
题型:选择题

恶性纤维组织细胞瘤来源于()。

A.成骨细胞

B.骨髓细胞

C.破骨细胞

D.软骨细胞

E.组织细胞

题型:选择题

Finding the right school for your child is a process. You will want to read about the school, talk to any friends who are involved in the school and, most important of all, visit the school.

The first step in finding out about Indian Creek is to request an information packet. We will be happy to send you a packet containing a brochure(小册子), the fee structure and an application. The packet should answer most of your general questions about the school.

In order to get a true sense of Indian Creek School, you should come for an Admission Tour, which includes a personal meeting focusing on your child, a tour of the building and the classrooms, and a discussion of the curriculum(课程).

This visit is no less important if the child for whom you are seeking admission is a teenager than if he or she is a three-year-old one. Every school has a different “school climate.” If you visit two or three schools, you will notice that each “feels” different. You know your child best and you will quickly develop a sense of whether a school is the right match or not.

●The initial point of entry for Indian Creek Students is at the pre-kindergarten level for three year olds.

●Children must be three years old by August 31st.

●We also have major points of entry from grade six to grade nine. At each of these levels, we open new sections and accept students in addition to those moving up from our own lower grades.

●There are scattered(零散的) openings available throughout the program due to attrition(学生流失). Once an opening occurs, students spend a day at ICS, part of which includes admission testing.

小题1:You can NOT get to know about ICS by      

A.getting an information packet

B.taking an admission tour

C.asking friends involved in ICS

D.taking an admission test小题2:During the Admission Tour, you can      

A.having a meeting with the children

B.decide on the design of the classrooms

C.talk with the school about the courses

D.choose the weather suitable for study.小题3:Which of the following is NOT accepted for ICS when there is no attrition?

A.A boy who will be 3 years old by July.

B.A fifth grader originally studying in ICS.

C.An eighth grader from another school.

D.A fourth grader from another school.小题4:The text is intended for      

A.teachers

B.parents

C.kindergarteners

D.school kids

题型:选择题

钓藤饮2功效与作用

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调度自动化主站系统“计算数据不刷新”,该故障属于()

A.SCADA类故障

B.前置类故障

C.应用类故障

D.网络类故障

题型:选择题

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