There have been（）periods in the develo

1、In general，the most effective period f

In general，the most effective period for observing stars and planets occurs during the darker limit of（）.AsunsetBcivil twilightCnautical twilightDastronomical twilight

2、There have been many（）in their marriag

There have been many（）in their marriage but they still love each other.Aright and wrongBback and forthCups and downsDright and left

3、Some of the TestKing routers have been

Some of the TestKing routers have been configured with default routes. What are some of the advantages of using default routes?（）A They estab...

4、Having been on the（）for the whole mon

Having been on the（）for the whole month, the criminal decided to turn himself in to the police.AescapedBcaughtCwayDru

5、There have been（）medicine in the last

There have been（）medicine in the last 50 years.Agreat advancesinBa great advanceinCgreat advanceonDa great advanceo

6、You are entering port and have been in

You are entering port and have been instructed to anchor，as your berth is not yet available.You are on a SW’ly heading，preparing to drop an...