Recognize more openers of secondary clauses in mainClause

src/3-three/sentences/parse/mainClause.js

@@ -1,5 +1,6 @@
 // if a clause starts with these, it's not a main clause
-const subordinate = `(after|although|as|because|before|if|since|than|that|though|when|whenever|where|whereas|wherever|whether|while|why|unless|until|once)`
+// followed by a number, 'since' or 'once' is a preposition or an adverb ('since 2010', 'once upon a time')
+const subordinate = `(after|although|as|because|before|if|since|than|that|though|when|whenever|where|whereas|wherever|whether|while|why|unless|until|once) !(#Value|upon|then|now)`
 const relative = `(that|which|whichever|who|whoever|whom|whose|whomever)`
 
 // a subordinator or relative pronoun only makes the clause secondary when it
@@ -34,6 +35,7 @@ const mainClause = function (s) {
   m = m.ifNo('^so that')
   m = m.ifNo('^rather than')
   m = m.ifNo('^provided that')
+  m = m.ifNo('^in case')
   if (m.length === 1) {
     return m
   }
@@ -55,6 +57,13 @@ const mainClause = function (s) {
     return m
   }
 
+  // an infinitive or an inverted condition ('To win ...', 'Had I known ...')
+  m = m.ifNo('^to #Infinitive')
+  m = m.ifNo('^#Condition')
+  if (m.length === 1) {
+    return m
+  }
+
   // did we go too far?
   if (m.length === 0) {
     m = s