you can use the following:

OR conjunction: word1, word2

AND conjunction: "word1", "word2"

For me it's a fatal error if MS missed the capability to do phrase
searching. I tried several times, but the search  result is far from
satisfied. Even the previous index server has this capability.

Any idea how to handle this problem?

why are you trying to re-invent the wheel here? Can
this be standardised or at least be made more clear. OR is OR and AND
is AND, or isn't (aint!) it? How do I search  for "Roland, Martin or
anybody" in a sharepoint document? And even if I can figure it out --
"Roland", "Martin", "or", "anybody" would be close, but not only find
the whole phrase --, how does a normal office worker figure that out?
After all, we want everybody in an org to use this, not just the
developers or techies...

What do you mean exactly? ARe you using FREETEXT or CONTAINS predicate in
your search  query?

Using the CONTAINS predicate, you are essentially forced to use boolean
searching for anything other than a phrase search. Phrase search is the
default behavior, so it is certainly there. To use boolean  and a mix of
phrase and/or word searches, surround the terms with quotation marks.

"exchange server" AND NOT "outlook"
would easily pull up all content with the phrase "exchange server" but not
containing the word outlook

BOOLEANS include AND, NOT, OR, NEAR

By the way, you can also do inflectional forms, although it isn't the
default like with FREETEXT
We are very happy with the phrase search capabilities.