A．fter a fire has been extinguished in a closed space, personnel may safely enter the space when

A．smoke density has been decreased sufficiently to see the bulkhead opposite the compartment's entrance

B．a lifeline and explosion proof flash light are used

C．all smoke and toxic fumes are removed and an adequate oxygen supply is present

D．overhaul has been completed to remove any possible source of re-ignition

Washington is home to lots of trees — it is the Evergreen State, after all — and

[单选题]He has been ______ for nearly three weeks after the death of his dear pet.A

[单选题]After knowing his partner has been under arrest，he( )his crime.A.concededB.

[单选题]After knowing his partner has been under arrest，he( )his crime.A.concededB.

This place has been ____ after the Second World War.A.refilledB.rearrangedC.reun

____ she worked for us as a secretary，but she has been promoted to administratio

[单选题]After knowing his partner has been under arrest，he( )his crime.A.concededB.

[单选题]After knowing his partner has been under arrest，he( )his crime.A.concededB.

____ she worked for us as a secretary,but she has been promoted to administratio

He has _______ been to Shanghai，has he？（ ）A. alreadyB. neverC. everD. still