托福考试

【单选题】
A、They have difficulty identifying these cells.
B．They aren’’t sure how these cells work.
C．They’’ve learned how to reproduce these cells.
D．They’’ve found similar cells in other species.

网考网参考答案：B
网考网解析：
What does the professor say about scientists who study the specialized cells in human bones document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>