U.S. Trade Representative Michael Froman said China needs to narrow its list of proposed exceptions to a proposed bilateral investment treaty, a key part of the U.S.-China economic relationship. "China's revised negative list is better than its initial one and certainly represents serious efforts by senior Chinese leaders, but still we are a substantial distance from the kind of high standard agreement necessary to achieve our mutual objectives," he said at an event at the Center for Strategic and International Studies in Washington.