设置文件student.dat具有的只读属性的DOS命令是（）。

A:ATTRIB+Hstudent.dat B:ATTRIB+Asmdent.dat C:ATTRIB+Sstudent.dat D:ATTRIB+Rsmdent.dat

请选出所有能将文件a.dat的权限从’rwx------’改为’rwxr-x---’的命令。（）

A:chownrwxr-x---dat B:chmodrwxr-x---dat C:chmodg+rxdat D:chmod750dat

SEACLOUD INVESTMENTS
A member of the "life for living" group
Planning for a creative retirement
Plan now for a retirement which will allow you to live proactively and creatively!
Dear Ms. Reid,
What happens when you retire Are you just going to let all that experience, all those qualifications, and all that creative energy slide into oblivion Seacloud’s Creative Retirement Advisory Services can design a package for you which includes but goes far beyond financial independence. Why don’t you come to one of our free introductory sessions to find out what "creative retirement" can mean
Here’s the basic idea: "creative retirement" planning has three essential dimensions. The first is financial independence. The second is health and balance. And the last, equally important dimension is creativity.
Take this opportunity to hear the inspirational founder of Seacloud Investments, Brenton McLeod, at a special free seminar. Your life may never be the same again!

Please contact your sales representative for further details.
SEACLOUD INVESTMENTS
5th floor, 56 Albert Rd.
Chicago, lllnois
Tel: 755-3265
Fax: 755-2222
Toll free 1-800-874-5330

A:The seminar date B:The lunch menu C:The place of the seminar D:The main speaker

语句ofstream f(“DAT

A:DAT”，ios_base：：app B:ios_base：：binary)；的功能是建立流对象f，并试图打开文件DATDAT并与之连接，而且( )。若文件存在，将文件指针定位于文件首；若文件不存在，建立一个新文件 C:若文件存在，将其截为空文件，若文件不存在，打开失败 D:若文件存在，将文件指针定位于文件尾；若文件不存在，建立一个新文件 E:若文件存在，打开失败；若文件不存在，建立一个新文件

语句ofstream f(“DAT

A:DAT”，ios_base：：app B:ios_base：：binary)；的功能是建立流对象f，并试图打开文件DATDAT并与之连接，而且( )。若文件存在，将文件指针定位于文件首；若文件不存在，建立一个新文件 C:若文件存在，将其截为空文件，若文件不存在，打开失败 D:若文件存在，将文件指针定位于文件尾；若文件不存在，建立一个新文件 E:若文件存在，打开失败；若文件不存在，建立一个新文件

SEACLOUD INVESTMENTS
A member of the "life for living" group
Planning for a creative retirement
Plan now for a retirement which will allow you to live proactively and creatively!
Dear Ms. Reid,
What happens when you retire Are you just going to let all that experience, all those qualifications, and all that creative energy slide into oblivion Seacloud’s Creative Retirement Advisory Services can design a package for you which includes but goes far beyond financial independence. Why don’t you come to one of our free introductory sessions to find out what "creative retirement" can mean
Here’s the basic idea: "creative retirement" planning has three essential dimensions. The first is financial independence. The second is health and balance. And the last, equally important dimension is creativity.
Take this opportunity to hear the inspirational founder of Seacloud Investments, Brenton McLeod, at a special free seminar. Your life may never be the same again!

Please contact your sales representative for further details.
SEACLOUD INVESTMENTS
5th floor, 56 Albert Rd.
Chicago, lllnois
Tel: 755-3265
Fax: 755-2222
Toll free 1-800-874-5330

A:The seminar date B:The lunch menu C:The place of the seminar D:The main speaker