题目

精子和卵细胞经过受精作用形成受精卵，在受精卵细胞中( ) A．细胞核的遗传物质完全来自卵细胞          B．细胞质中的遗传物质完全来自卵细胞 C．细胞核和细胞质中的遗传物质都平均来自精子和卵细胞 D．细胞中营养由精子和卵细胞共同提供 答案：B--What happened in that store? -- A thief _____ by the policeman just now. A. is caught     B. caught      C. has caught     D. was caught