地铁及轨道工程中SMW工法围护结构的特点主要表现在( )。

A．止水性差

B．构造简单

C．施工速度快

D．型钢可以部分回收

E．型钢插入深度一般大于搅拌桩深度

A CFA charterholder owns an asset management firm with offices downtown. To minimize rent expenses, each year the charterholder ships the previous year’s research report to a nearby warehouse. There, the reports are digitized and stored in both electronic and hard-copy forms. After five years, all paper copies are destroyed and only electronic copies are retained. Are the charterholder’s record-retention procedures in compliance with the CFA Institute Standards of Practice（）

A. No.

B. Yes, because he is only required to retain hard copies for five years.

C. Yes, because he still retains electronic copies of the original documents.