楼主不要着急，你说的 FORM I-94 的D/S的意识是：DURATION OF STATUS (D/S)，不是决绝你入境，但是你要看清楚上边对你的限制和可以停留到什么时候。
The immigration officer at the U.S. port of entry makes a decision on your admission, the length and conditions of your stay, and will record the terms of your admission on the form “Arrival/Departure Record” (I-94 Form) as well as in your passport.
The I-94 Form is a small white card. The immigration officer usually staples this form into your passport.
In certain visa categories such as students and exchange visitors, the alien may be admitted into the U.S. for as long as the person is still doing the activity for which the visa was issued, rather than being admitted until a specific departure dates. This is called admission for "duration of status".
Students arriving on F-1/J-1 visas are generally admitted for “Duration of Status.” It is indicated on the Form I-94 as “D/S” (Duration of Status). It means they are authorized to stay in the U.S. while maintaining their visa status (enrolled in a full course of study, engaged in practical training or in their post-completion grace period).
The I-94 form also has a number that the immigration officer will use to keep track of your entry/exits. Make sure that you do not lose this card! Every time you leave the U.S., you must return the I-94 form to the immigration officer. Upon your re-entry, you will receive a new one. As an exception, you can keep your current I-94 form when you travel to Canada, Mexico, or certain adjacent islands for 30 days or less. However, it is always advisable to verify this at the border.
如果你签证就到20号那20就必须回去续签，如果不是多留几天也无妨，记住千万不要留过签证日期就对了，不然将来解释起来很麻烦的。
祝福你好运气吧！: )
