Help with complex CAML query

I am wondering if the following CAML query structure is correct: I appreciate your help.

<Query>
  <CalendarDate><Today/></CalendarDate>
  <Where>
    <And>
      <And>
        <IsNotNull>
          <FieldRef Name="Unit" />      
        </IsNotNull>
      </And>    
      <DateRangesOverlap>
        <FieldRef Name="EventDate" />
        <FieldRef Name="EndDate" />
        <FieldRef Name="RecurrenceID" />
        <Value Type="DateTime">
          <Today />
        </Value>
      </DateRangesOverlap>
    </And>
    <And>
      <IsNotNull>
        <FieldRef Name="Primary_x0020_Expertise" />              
      </IsNotNull>
      <Or>
        <IsNotNull>
          <FieldRef Name="Secondary_x0020_Expertise" />
        </IsNotNull>
      </Or>
    </And>
  </And>
  </And>
  </Where>
  <OrderBy>
    <FieldRef Name="EventDate" />
  </OrderBy>
</Query>

CAMLQueryOptions:
<QueryOptions>
  <CalendarDate><Today/></CalendarDate>
  <RecurrencePatternXMLVersion>v3</RecurrencePatternXMLVersion>
  <ExpandRecurrence>TRUE</ExpandRecurrence>
</QueryOptions>