adj.按部就班的;按步;步进;
例句:
Step by step, they were getting to the top.
他们一步步地接近山顶.
This may appear complex, so we shall explain It'step by step.
它似乎很复杂, 因此我们将逐步地加以说明.
Step by step, she had separated one material from another.
玛丽一步一步地将一种物质从另一种物质中分离出来.