I saw a woman running toward me in the dark.Before I could recognize who she was, she had run back in the direction _______ she had come.

A．of which

B．by which

C．in which

D．from which

硫化氢(H₂S)分子中，两个H—S键夹角都接近90°，说明H₂S分子的空间构型为__________；二氧化碳 (CO₂)分子中，两个C=O键夹角是180°，说明二氧化碳分子的空间构型为____________；甲烷(CH₄)分子中，任意两个C-H键的夹角都是109°28’，说明CH₄分子的空间构型为

_______。