找到答案了：原来在网页导航“FAQ”问题解答里第一条就说明了：
Question: I want to trade LTC for USD but I don't see that currency pair on the right side of the screen?Per default only trading to and from BTC is shown. If you would like to trade in any other currency pair go to your user settings (choose "Settings" from the top of the menu) Then select the Layout tab. You should see a checkbox called "Show only BTC rates". Uncheck this to see all currency combinations.
问：我想换LTC美元，但我没有看到该货币对在右侧的显示？
默认情况下，只有BTC交易。如果您想交易的任何其他货币对您的用户设置（从顶部的菜单中选择“设置”），然后选择“版式”选项卡。你应该看到一个复选框被称为“只显示BTC率”。取消选中此看到所有的货币组合。
即点击右上角的“设置”→将“Show only BTC rates（只显示BTC费率）”不选中复选框，就可以了。
