二级的英文：
dipole
ambipolar
second

A piloted two-stage spaceplane using existing technology will then be seen as among the all-time best aerospace buys
而且，采用现有技术研制的由宇航员驾驶的二级太空飞机将被视为空前便宜的航天器之一。

Second class highway
(二级公路)

Parallel market
二级市场

Gales of hurricane force
十二级的大风.

There 's a light east breeze coming up.
吹起了二级东风

What secondary structure predominates in this Fab fragment?
Fab片段中的主要二级结构是什么?

This spatial configuration of the polypeptide chain is the secondary structure.
肽链的这个空间构象就是二级结构。

Organic light emitting diode
有机发光二级管,[台]有机发光二极管

This shop sold the clear flour last week.
这家店上周还买二级面粉呢。

It is possible to use a plutonium foil as a filter to remove the second-order contamination
可用钚箔作为过滤器消除二级干扰。

Forbidden transitions are those for which dipole radiative transitions are not allowed by the selection rules
禁戒跃迁指的是选择定则所不容许的偶极辐射跃迁。

Any heteronuclear diatomic molecule must have a dipole moment since its two ends are different
任何异核双原子分子必然具有偶极矩，因为它的两端是不同的。

The dipole oscillator sum can be expressed in terms of the integrated photo absorption cross section
偶极谐振子和可以用积分后的光子吸收截面来表示。

the second in command
副司令员

grounded to the second baseman.
打到二垒手位置的滚地球

Down Second Avenue
沿着第二条林荫大道走去