参考答案：许多美国公司现在知道他们必须了解/学习中国的法律，贸易惯例/做法和文化，以便在与他们的新贸易伙伴
做生意时更有效率。

解析：
Many American companies now understand that they must study Chinese laws, trade practices, and culture in order to be more effective in doing business with their new trading partners.