人体内某一细胞正在进行减数分裂，其内有44个常染色体与两个X染色体，此细胞不可能是（ ）
①初级精母细胞 ②次级精母细胞 ③初级卵母细胞 ④卵细胞．
“魔术塑料积木”可以开发智力、发挥想像空间．如图是小明用六个棱长为1的立方块组成的一个几何体，其俯视图的面积是____
Telephone: 3324545
Address: East Road
Open: Mon. to Fri. 7:30 am—2:30 pm and 5:00 pm—9:00 pm
Sat. 7:30am—2:00pm and 5:00 pm---9:30 pm
Sun. 11:00 am---2:00pm and 5:00 pm –9:30 pm
Telephone: 3351352
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Telephone: 3374398
Address: Peace Road
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Telephone: 3368432
Address: West Road
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下列变化中一定没有发生化学变化的是（ ）
