at one's/sb.'s elbow

1. 在(某人)手边

She stayed up all night writing the paper with a pot of coffee at her elbow.

她熬了一整夜写论文, 身边放着一壶咖啡。

up to the/one's elbows

1. 非常忙; 深深卷入

She was up to her elbows in preparing dinner when the doorbell rang.

门铃响时她正在为准备晚饭忙得不可开交。