Someone was opening the door. It was Brently Mallard, who entered, looking dirty and tired, carrying a suitcase and an umbrella. He was not killed in the accident. He didn't even know there had been one. He stood surprised at Josephine's sudden cry. He didn't understand why Richards moved suddenly between them, to hide Louise from her husband.
to hide Louise from her husband这里做状语为什么用逗号隔开?