问题
选择题
Students in Dingli Senior High School are walking along the street, _____ a small red flag.
A．they each hold
B．each holds
C．each of them holds
D．each holding
答案
答案：D
考查独立主格结构。如果选择ABC都需要加连词and;因为两个句子之间必须要有连词连接。答案为D，这是一个独立主格结构，它是一个短语，相当于一个句子。本题中each holding a small red flag="and" each holds="and" each of them hold="and" they each hold.