Steven Mnuchin testifies before U.S. Senate Finance Committee in a hearing on his nomination as Treasury Secretary at Capitol Hill in Washington D.C., the United States, on Jan. 19, 2017. Steven Mnuchin, U.S. President-elect Donald Trump's nominee for Treasury Secretary, said on Thursday that it was important to keep the U.S. dollar strong in the long term, walking back Trump's earlier comments on the U.S. currency. (Xinhua/Bao Dandan)